Console: Update rrd4j to version 3.9

LICENSE.txt

@@ -267,7 +267,7 @@ Applications:
    See licenses/LICENSE-Apache2.0.txt
    See licenses/LICENSE-ECLIPSE-1.0.html
 
-   RRD4J 3.8 (jrobin.jar):
+   RRD4J 3.9 (jrobin.jar):
    Copyright (c) 2001-2005 Sasa Markovic and Ciaran Treanor.
    Copyright (c) 2011 The OpenNMS Group, Inc.
    Copyright 2011 The RRD4J Authors.

apps/jrobin/java/src/com/tomgibara/crinch/hashing/PerfectStringHash.java

@@ -184,7 +184,7 @@ public class PerfectStringHash implements Hash<String> {
      *            such that <code>hash(values[i]) == i</code>.
      */
 
-    public PerfectStringHash(final String values[]) {
+    public PerfectStringHash(final String[] values) {
         final int length = values.length;
         if (length == 0) throw new IllegalArgumentException("No values supplied");
 
@@ -242,7 +242,7 @@ public class PerfectStringHash implements Hash<String> {
         final int[] pivots = new int[offset * 2];
         for (int i = 0; i < length;) {
             final int runLength = runLengths[i];
-            if (runLength > 1)  generatePivots(values, i, runLength, pivots, (int) offsets[i << 1]);
+            if (runLength > 1)  generatePivots(values, i, runLength, pivots, offsets[i << 1]);
             i += runLength;
         }
 

apps/jrobin/java/src/org/rrd4j/core/ArcDef.java

@@ -14,7 +14,6 @@ import org.rrd4j.ConsolFun;
  * </ul>
  * For the complete explanation of all archive definition parameters, see RRDTool's
  * <a href="http://oss.oetiker.ch/rrdtool/doc/rrdcreate.en.html" target="man">rrdcreate man page</a>
- * 
  *
  * @author Sasa Markovic
  */

apps/jrobin/java/src/org/rrd4j/core/ArcState.java

@@ -9,10 +9,10 @@ import java.io.IOException;
  * @author Sasa Markovic
  */
 public class ArcState implements RrdUpdater<ArcState> {
-    private Archive parentArc;
+    private final Archive parentArc;
 
-    private RrdDouble<ArcState> accumValue;
-    private RrdLong<ArcState> nanSteps;
+    private final RrdDouble<ArcState> accumValue;
+    private final RrdLong<ArcState> nanSteps;
 
     ArcState(Archive parentArc, boolean shouldInitialize) throws IOException {
         this.parentArc = parentArc;

apps/jrobin/java/src/org/rrd4j/core/Archive.java

@@ -143,7 +143,7 @@ public class Archive implements RrdUpdater<Archive> {
             }
         }
         // update robin in bulk
-        int bulkUpdateCount = (int) Math.min(numUpdates / steps.get(), (long) rows.get());
+        int bulkUpdateCount = (int) Math.min(numUpdates / steps.get(), rows.get());
         robin.bulkStore(value, bulkUpdateCount);
         // update remaining steps
         long remainingUpdates = numUpdates % steps.get();

apps/jrobin/java/src/org/rrd4j/core/DataHolder.java

@@ -17,7 +17,7 @@ public interface DataHolder {
     * Constant that defines the default {@link RrdDbPool} usage policy. Defaults to <code>false</code>
     * (i.e. the pool will not be used to fetch data from RRD files)
     */
-   public static final boolean DEFAULT_POOL_USAGE_POLICY = false;
+   boolean DEFAULT_POOL_USAGE_POLICY = false;
 
     /**
      * Returns boolean value representing {@link org.rrd4j.core.RrdDbPool RrdDbPool} usage policy.
@@ -164,7 +164,7 @@ public interface DataHolder {
     /**
      * Creates a datasource that performs a variable calculation on an
      * another named datasource to yield a single combined timestamp/value.
-     *
+     * <p>
      * Requires that the other datasource has already been defined; otherwise, it'll
      * end up with no data
      *

apps/jrobin/java/src/org/rrd4j/core/Datasource.java

@@ -28,9 +28,9 @@ public class Datasource implements RrdUpdater<Datasource> {
     private final RrdDouble<Datasource> minValue, maxValue;
 
     // state variables
-    private RrdDouble<Datasource> lastValue;
-    private RrdLong<Datasource> nanSeconds;
-    private RrdDouble<Datasource> accumValue;
+    private final RrdDouble<Datasource> lastValue;
+    private final RrdLong<Datasource> nanSeconds;
+    private final RrdDouble<Datasource> accumValue;
 
     Datasource(RrdDb parentDb, DsDef dsDef) throws IOException {
         boolean shouldInitialize = dsDef != null;
@@ -476,4 +476,3 @@ public class Datasource implements RrdUpdater<Datasource> {
         return parentDb.getRrdAllocator();
     }
 }
-

apps/jrobin/java/src/org/rrd4j/core/FetchData.java

@@ -1,9 +1,10 @@
 package org.rrd4j.core;
 
 import java.io.ByteArrayOutputStream;
-import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Paths;
 
 import org.rrd4j.ConsolFun;
 import org.rrd4j.data.Aggregates;
@@ -43,14 +44,14 @@ public class FetchData {
     // anything funny will do
     private static final String RPN_SOURCE_NAME = "WHERE THE SPEECHLES UNITE IN A SILENT ACCORD";
 
-    private FetchRequest request;
+    private final FetchRequest request;
     private String[] dsNames;
     private long[] timestamps;
     private double[][] values;
 
-    private Archive matchingArchive;
-    private long arcStep;
-    private long arcEndTime;
+    private final Archive matchingArchive;
+    private final long arcStep;
+    private final long arcEndTime;
 
     FetchData(Archive matchingArchive, FetchRequest request) throws IOException {
         this.matchingArchive = matchingArchive;
@@ -279,7 +280,7 @@ public class FetchData {
     }
 
     private static String padWithBlanks(String input, int width) {
-        StringBuilder buff = new StringBuilder("");
+        StringBuilder buff = new StringBuilder();
         int diff = width - input.length();
         while (diff-- > 0) {
             buff.append(' ');
@@ -350,11 +351,10 @@ public class FetchData {
      * @param rpnExpression RRDTool-like RPN expression
      * @return Object containing all aggregated values
      * @throws java.lang.IllegalArgumentException Thrown if invalid RPN expression is supplied
-     * @throws java.io.IOException if any.
      * @deprecated This method is deprecated. Uses instance of {@link org.rrd4j.data.Variable}, used with {@link org.rrd4j.data.DataProcessor#addDatasource(String, String, Variable)}
      */
     @Deprecated
-    public Aggregates getRpnAggregates(String rpnExpression) throws IOException {
+    public Aggregates getRpnAggregates(String rpnExpression) {
         DataProcessor dataProcessor = createDataProcessor(rpnExpression);
         return dataProcessor.getAggregates(RPN_SOURCE_NAME);
     }
@@ -402,9 +402,8 @@ public class FetchData {
      * Dumps fetch data to output stream in XML format. A flush is issued at the end of the xml generation.
      *
      * @param outputStream Output stream to dump fetch data to
-     * @throws java.io.IOException Thrown in case of I/O error
      */
-    public void exportXml(OutputStream outputStream) throws IOException {
+    public void exportXml(OutputStream outputStream) {
         //No auto flush for XmlWriter, it will be flushed once, when export is finished
         try (XmlWriter writer = new XmlWriter(outputStream, false)) {
             writer.startTag("fetch_data");
@@ -447,7 +446,7 @@ public class FetchData {
      * @throws java.io.IOException Thrown in case of I/O error
      */
     public void exportXml(String filepath) throws IOException {
-        try(OutputStream outputStream = new FileOutputStream(filepath)) {
+        try (OutputStream outputStream = Files.newOutputStream(Paths.get(filepath))) {
             exportXml(outputStream);
         }
     }
@@ -456,9 +455,8 @@ public class FetchData {
      * Dumps fetch data in XML format.
      *
      * @return String containing XML formatted fetch data
-     * @throws java.io.IOException Thrown in case of I/O error
      */
-    public String exportXml() throws IOException {
+    public String exportXml() {
         ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
         exportXml(outputStream);
         return outputStream.toString();

apps/jrobin/java/src/org/rrd4j/core/FetchRequest.java

@@ -17,11 +17,11 @@ import java.util.Set;
  * @author Sasa Markovic
  */
 public class FetchRequest {
-    private RrdDb parentDb;
-    private ConsolFun consolFun;
-    private long fetchStart;
-    private long fetchEnd;
-    private long resolution;
+    private final RrdDb parentDb;
+    private final ConsolFun consolFun;
+    private final long fetchStart;
+    private final long fetchEnd;
+    private final long resolution;
     private String[] filter;
 
     FetchRequest(RrdDb parentDb, ConsolFun consolFun, long fetchStart, long fetchEnd, long resolution) {
@@ -74,7 +74,7 @@ public class FetchRequest {
      * @param filter Set of datasource names to fetch data for.
      */
     public void setFilter(Set<String> filter) {
-        this.filter = filter.toArray(new String[filter.size()]);
+        this.filter = filter.toArray(new String[0]);
     }
 
     /**

apps/jrobin/java/src/org/rrd4j/core/Header.java

@@ -23,18 +23,19 @@ public class Header implements RrdUpdater<Header> {
     static final String RRDTOOL_VERSION3 = "0003";
     private static final String[] VERSIONS = {"version 0.1", "version 0.2"};
 
-    private RrdDb parentDb;
+    private final RrdDb parentDb;
     private int version = -1;
 
-    private RrdString<Header> signature;
-    private RrdLong<Header> step;
-    private RrdInt<Header> dsCount, arcCount;
-    private RrdLong<Header> lastUpdateTime;
+    private final RrdString<Header> signature;
+    private final RrdLong<Header> step;
+    private final RrdInt<Header> dsCount;
+    private final RrdInt<Header> arcCount;
+    private final RrdLong<Header> lastUpdateTime;
 
     Header(RrdDb parentDb, RrdDef rrdDef) throws IOException {
         this.parentDb = parentDb;
 
-        String initSignature = null;
+        String initSignature;
         if(rrdDef != null) {
             version = rrdDef.getVersion(); 
             initSignature = SIGNATURE + ", " + VERSIONS[version - 1];

apps/jrobin/java/src/org/rrd4j/core/RobinArray.java

@@ -1,6 +1,7 @@
 package org.rrd4j.core;
 
 import java.io.IOException;
+import java.util.Arrays;
 
 /**
  * Class to represent archive values for a single datasource. Robin class is the heart of
@@ -18,7 +19,7 @@ class RobinArray implements Robin {
     private final Archive parentArc;
     private final RrdInt<Robin> pointer;
     private final RrdDoubleArray<Robin> values;
-    private int rows;
+    private final int rows;
 
     RobinArray(Archive parentArc, int rows, boolean shouldInitialize) throws IOException {
         this.parentArc = parentArc;
@@ -104,9 +105,7 @@ class RobinArray implements Robin {
     /** {@inheritDoc} */
     public void setValues(double newValue) throws IOException {
         double[] values = new double[rows];
-        for (int i = 0; i < values.length; i++) {
-            values[i] = newValue;
-        }
+        Arrays.fill(values, newValue);
         update(values);
     }
 

apps/jrobin/java/src/org/rrd4j/core/RobinMatrix.java

@@ -1,6 +1,7 @@
 package org.rrd4j.core;
 
 import java.io.IOException;
+import java.util.Arrays;
 
 /**
  * Class to represent archive values for a single datasource. Robin class is the heart of
@@ -18,10 +19,10 @@ class RobinMatrix implements Robin {
     private final Archive parentArc;
     private final RrdInt<Archive> pointer;
     private final RrdDoubleMatrix<Archive> values;
-    private int rows;
-    private int column;
+    private final int rows;
+    private final int column;
 
-    RobinMatrix(Archive parentArc, RrdDoubleMatrix<Archive> values, RrdInt<Archive> pointer, int column) throws IOException {
+    RobinMatrix(Archive parentArc, RrdDoubleMatrix<Archive> values, RrdInt<Archive> pointer, int column) {
         this.parentArc = parentArc;
         this.pointer = pointer; 
         this.values = values;
@@ -101,9 +102,7 @@ class RobinMatrix implements Robin {
      */
     public void setValues(double newValue) throws IOException {
         double[] values = new double[rows];
-        for (int i = 0; i < values.length; i++) {
-            values[i] = newValue;
-        }
+        Arrays.fill(values, newValue);
         update(values);
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdAllocator.java

@@ -1,7 +1,5 @@
 package org.rrd4j.core;
 
-import java.io.IOException;
-
 /**
  * An internal usage class.
  *
@@ -14,7 +12,7 @@ public class RrdAllocator {
         super();
     }
 
-    long allocate(long byteCount) throws IOException {
+    long allocate(long byteCount) {
         long pointer = allocationPointer;
         allocationPointer += byteCount;
         return pointer;

apps/jrobin/java/src/org/rrd4j/core/RrdBackend.java

@@ -239,8 +239,8 @@ public abstract class RrdBackend {
         int count = values.length;
         byte[] image = new byte[8 * count];
         int k = 0;
-        for (int i = 0; i < count; i++) {
-            byte[] b = getDoubleBytes(values[i]);
+        for (double value : values) {
+            byte[] b = getDoubleBytes(value);
             image[k++] = b[0];
             image[k++] = b[1];
             image[k++] = b[2];

apps/jrobin/java/src/org/rrd4j/core/RrdBackendAnnotation.java

@@ -18,7 +18,7 @@ import java.lang.annotation.Target;
 @Retention(RUNTIME)
 @Target(TYPE)
 public @interface RrdBackendAnnotation {
-    public static boolean DEFAULT_CACHING_ALLOWED = true;
+    boolean DEFAULT_CACHING_ALLOWED = true;
     String name();
     boolean cachingAllowed() default DEFAULT_CACHING_ALLOWED;
     String scheme() default "";

apps/jrobin/java/src/org/rrd4j/core/RrdBackendFactory.java

@@ -27,7 +27,7 @@ import java.util.stream.Stream;
  *
  * Factory classes are used to create concrete {@link org.rrd4j.core.RrdBackend} implementations.
  * Each factory creates unlimited number of specific backend objects.
- *
+ * <p>
  * Rrd4j supports six different backend types (backend factories) out of the box:
  * <ul>
  * <li>{@link org.rrd4j.core.RrdRandomAccessFileBackend}: objects of this class are created from the
@@ -88,7 +88,7 @@ public abstract class RrdBackendFactory implements Closeable {
             factories.put(safeFactory.name, safeFactory);
             defaultFactory = factories.get(DEFAULTFACTORY);
         }
-        private static RrdBackendFactory defaultFactory;
+        private static final RrdBackendFactory defaultFactory;
     }
 
     /**
@@ -541,10 +541,9 @@ public abstract class RrdBackendFactory implements Closeable {
      * Determines if the header should be validated.
      *
      * @param path Storage path
-     * @throws java.io.IOException if header validation fails
      * @return a boolean.
      */
-    protected boolean shouldValidateHeader(String path) throws IOException {
+    protected boolean shouldValidateHeader(String path) {
         return validateHeader;
     }
 
@@ -552,10 +551,9 @@ public abstract class RrdBackendFactory implements Closeable {
      * Determines if the header should be validated.
      *
      * @param uri Storage URI
-     * @throws java.io.IOException if header validation fails
      * @return a boolean.
      */
-    protected boolean shouldValidateHeader(URI uri) throws IOException {
+    protected boolean shouldValidateHeader(URI uri) {
         return shouldValidateHeader(getPath(uri));
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdByteArrayBackend.java

@@ -64,10 +64,9 @@ public abstract class RrdByteArrayBackend extends ByteBufferBackend {
      * {@inheritDoc}
      *
      * <p>It will reserves a memory section as a RRD storage.</p>
-     * 
-     * @throws java.lang.IllegalArgumentException if length is bigger that the possible length.
+     *
      */
-    protected void setLength(long length) throws IOException {
+    protected void setLength(long length) {
         if (length < 0 || length > Integer.MAX_VALUE) {
             throw new IllegalArgumentException("Illegal length: " + length);
         }

apps/jrobin/java/src/org/rrd4j/core/RrdDb.java

@@ -131,7 +131,7 @@ public class RrdDb implements RrdUpdater<RrdDb>, Closeable {
             try (DataImporter rrdImporter = resoleImporter(externalPath, importer)) {
                 if (usePool) {
                     try (RrdDb db = resolvePool(pool).requestRrdDb(rrdUri, factory, importer)) {
-                    };
+                    }
                 } else {
                     try (RrdDb db = new RrdDb(path, rrdUri, null, rrdImporter, factory, null)) {
                     }
@@ -210,7 +210,7 @@ public class RrdDb implements RrdUpdater<RrdDb>, Closeable {
         }
 
         /**
-         * Internal method used to memorized the pool, without generating a loop
+         * Internal method used to memorize the pool, without generating a loop
          * @param pool
          * @return
          */
@@ -1220,7 +1220,7 @@ public class RrdDb implements RrdUpdater<RrdDb>, Closeable {
      * <p>
      * Use <code>original.xml</code> file to create the corresponding RRDTool file
      * (from your command line):
-     *
+     * <p>
      * <code>rrdtool restore copy.rrd original.xml</code>
      *
      * @param filename Path to XML file which will be created.

apps/jrobin/java/src/org/rrd4j/core/RrdDbPool.java

@@ -60,14 +60,14 @@ public class RrdDbPool {
         final Lock lock;
         final boolean placeholder;
         final URI uri;
-        RrdEntry(URI canonicalPath) throws InterruptedException {
+        RrdEntry(URI canonicalPath) {
             placeholder = false;
             uri = canonicalPath;
             inuse = new ReentrantReadWriteLock();
             lock = inuse.writeLock();
             waitempty = new CountDownLatch(1);
         }
-        RrdEntry(RrdEntry parent) throws InterruptedException {
+        RrdEntry(RrdEntry parent) {
             assert ! parent.placeholder;
             placeholder = true;
             uri = parent.uri;
@@ -243,7 +243,7 @@ public class RrdDbPool {
     }
 
     private enum ACTION {
-        SWAP, DROP;
+        SWAP, DROP
     }
 
     private void passNext(ACTION a, RrdEntry e) {
@@ -297,7 +297,7 @@ public class RrdDbPool {
             return;
         }
         URI dburi = rrdDb.getCanonicalUri();
-        RrdEntry ref = null;
+        RrdEntry ref;
         try {
             ref = getEntry(dburi, false);
         } catch (InterruptedException e) {
@@ -375,10 +375,9 @@ public class RrdDbPool {
      * Wait for a empty reference with no usage
      * @param uri
      * @return an reference with no usage 
-     * @throws IOException
      * @throws InterruptedException
      */
-    private RrdEntry waitEmpty(URI uri) throws IOException, InterruptedException {
+    private RrdEntry waitEmpty(URI uri) throws InterruptedException {
         RrdEntry ref = getEntry(uri, true);
         try {
             while (ref.count != 0) {
@@ -401,16 +400,14 @@ public class RrdDbPool {
      * @param uri
      * @return an reference with no usage 
      * @throws InterruptedException
-     * @throws IOException
      */
-    private RrdEntry requestEmpty(URI uri) throws InterruptedException, IOException {
-        RrdEntry ref = waitEmpty(uri);
-        return ref;
+    private RrdEntry requestEmpty(URI uri) throws InterruptedException {
+        return waitEmpty(uri);
     }
 
     RrdDb requestRrdDb(URI uri, RrdBackendFactory factory) throws IOException {
         uri = factory.getCanonicalUri(uri);
-        RrdEntry ref = null;
+        RrdEntry ref;
         try {
             ref = getEntry(uri, true);
 
@@ -625,10 +622,9 @@ public class RrdDbPool {
      *
      * @param rrdDb RrdDb reference for which informations is needed.
      * @return the number of request for this RRD.
-     * @throws java.io.IOException if any
      * @throws java.lang.IllegalStateException if the thread was interrupted
      */
-    public int getOpenCount(RrdDb rrdDb) throws IOException {
+    public int getOpenCount(RrdDb rrdDb) {
         return getCanonicalUriUsage(rrdDb.getCanonicalUri());
     }
 
@@ -638,10 +634,9 @@ public class RrdDbPool {
      *
      * @param path RRD's path for which informations is needed.
      * @return the number of request for this RRD.
-     * @throws java.io.IOException if any
      * @throws java.lang.IllegalStateException if the thread was interrupted
      */
-    public int getOpenCount(String path) throws IOException {
+    public int getOpenCount(String path) {
         return getCanonicalUriUsage(defaultFactory.getCanonicalUri(defaultFactory.getUri(path)));
     }
 
@@ -650,10 +645,9 @@ public class RrdDbPool {
      *
      * @param uri RRD's URI for which informations is needed.
      * @return the number of request for this RRD.
-     * @throws java.io.IOException if any
      * @throws java.lang.IllegalStateException if the thread was interrupted
      */
-    public int getOpenCount(URI uri) throws IOException {
+    public int getOpenCount(URI uri) {
         return getCanonicalUriUsage(checkFactory(uri).getCanonicalUri(uri));
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdDef.java

@@ -5,10 +5,10 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.net.URI;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.Calendar;
 import java.util.Date;
-import java.util.Iterator;
 import java.util.List;
 import java.util.StringTokenizer;
 
@@ -59,8 +59,8 @@ public class RrdDef {
     private long step = DEFAULT_STEP;
     private int version = DEFAULTVERSION;
 
-    private List<DsDef> dsDefs = new ArrayList<>();
-    private List<ArcDef> arcDefs = new ArrayList<>();
+    private final List<DsDef> dsDefs = new ArrayList<>();
+    private final List<ArcDef> arcDefs = new ArrayList<>();
 
     /**
      * <p>Creates new RRD definition object with the given path.
@@ -189,12 +189,19 @@ public class RrdDef {
 
     /**
      * Returns path for the new RRD. It's extracted from the URI. If it's an opaque URI, it return the scheme specific part.
+     * <br>
+     * It's not a reliable way to resolve an file path. Instead, one should use <code> Paths.get(def.getUri())</code>
+     * when the URI scheme is file.
      *
      * @return path to the new RRD which should be created
      */
     public String getPath() {
         if (uri.isOpaque()) {
             return uri.getSchemeSpecificPart();
+        } else if ("file".equals(uri.getScheme())) {
+            // Windows path from URI returns strange results.
+            // Ensure that's a compliant path
+            return Paths.get(uri).toString();
         } else {
             return uri.getPath();
         }
@@ -516,7 +523,7 @@ public class RrdDef {
      * @return Array of data source definition objects
      */
     public DsDef[] getDsDefs() {
-        return dsDefs.toArray(new DsDef[dsDefs.size()]);
+        return dsDefs.toArray(new DsDef[0]);
     }
 
     /**
@@ -584,13 +591,7 @@ public class RrdDef {
     }
 
     void saveSingleDatasource(String dsName) {
-        Iterator<DsDef> it = dsDefs.iterator();
-        while (it.hasNext()) {
-            DsDef dsDef = it.next();
-            if (!dsDef.getDsName().equals(dsName)) {
-                it.remove();
-            }
-        }
+        dsDefs.removeIf(dsDef -> !dsDef.getDsName().equals(dsName));
     }
 
     void removeArchive(ConsolFun consolFun, int steps) {

apps/jrobin/java/src/org/rrd4j/core/RrdDefTemplate.java

@@ -60,6 +60,7 @@ import java.util.Calendar;
  * <li>There is a strong relation between the XML template syntax and the syntax of
  * {@link org.rrd4j.core.RrdDef} class methods. If you are not sure what some XML tag means, check javadoc
  * for the corresponding class.
+ * <li>the path to the rrd can be specified either as a file path using path element or as an uri using a url tag</li>
  * <li>starting timestamp can be supplied either as a long integer
  * (like: 1000243567) or as an ISO formatted string (like: 2004-02-21 12:25:45)
  * <li>whitespaces are not harmful

apps/jrobin/java/src/org/rrd4j/core/RrdDouble.java

@@ -6,11 +6,11 @@ class RrdDouble<U extends RrdUpdater<U>> extends RrdPrimitive<U> {
     private double cache;
     private boolean cached = false;
 
-    RrdDouble(RrdUpdater<U> updater, boolean isConstant) throws IOException {
+    RrdDouble(RrdUpdater<U> updater, boolean isConstant) {
         super(updater, RrdDouble.RRD_DOUBLE, isConstant);
     }
 
-    RrdDouble(RrdUpdater<U> updater) throws IOException {
+    RrdDouble(RrdUpdater<U> updater) {
         super(updater, RrdDouble.RRD_DOUBLE, false);
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdDoubleArray.java

@@ -3,9 +3,9 @@ package org.rrd4j.core;
 import java.io.IOException;
 
 class RrdDoubleArray<U extends RrdUpdater<U>> extends RrdPrimitive<U> {
-    private int length;
+    private final int length;
 
-    RrdDoubleArray(RrdUpdater<U> updater, int length) throws IOException {
+    RrdDoubleArray(RrdUpdater<U> updater, int length) {
         super(updater, RrdPrimitive.RRD_DOUBLE, length, false);
         this.length = length;
     }

apps/jrobin/java/src/org/rrd4j/core/RrdEnum.java

@@ -7,12 +7,12 @@ class RrdEnum<U extends RrdUpdater<U>, E extends Enum<E>> extends RrdPrimitive<U
     private E cache;
     private final Class<E> clazz;
 
-    RrdEnum(RrdUpdater<U> updater, boolean isConstant, Class<E> clazz) throws IOException {
+    RrdEnum(RrdUpdater<U> updater, boolean isConstant, Class<E> clazz) {
         super(updater, RrdPrimitive.RRD_STRING, isConstant);
         this.clazz = clazz;
     }
 
-    RrdEnum(RrdUpdater<U> updater, Class<E> clazz) throws IOException {
+    RrdEnum(RrdUpdater<U> updater, Class<E> clazz) {
         this(updater, false, clazz);
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdInt.java

@@ -6,11 +6,11 @@ class RrdInt<U extends RrdUpdater<U>> extends RrdPrimitive<U> {
     private int cache;
     private boolean cached = false;
 
-    RrdInt(RrdUpdater<U> updater, boolean isConstant) throws IOException {
+    RrdInt(RrdUpdater<U> updater, boolean isConstant) {
         super(updater, RrdPrimitive.RRD_INT, isConstant);
     }
 
-    RrdInt(RrdUpdater<U> updater) throws IOException {
+    RrdInt(RrdUpdater<U> updater) {
         this(updater, false);
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdLong.java

@@ -6,11 +6,11 @@ class RrdLong<U extends RrdUpdater<U>> extends RrdPrimitive<U> {
     private long cache;
     private boolean cached = false;
 
-    RrdLong(RrdUpdater<U> updater, boolean isConstant) throws IOException {
+    RrdLong(RrdUpdater<U> updater, boolean isConstant) {
         super(updater, RrdPrimitive.RRD_LONG, isConstant);
     }
 
-    RrdLong(RrdUpdater<U> updater) throws IOException {
+    RrdLong(RrdUpdater<U> updater) {
         this(updater, false);
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdMemoryBackend.java

@@ -1,6 +1,5 @@
 package org.rrd4j.core;
 
-import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.util.Optional;
 import java.util.concurrent.atomic.AtomicReference;
@@ -21,11 +20,11 @@ public class RrdMemoryBackend extends ByteBufferBackend {
     protected RrdMemoryBackend(String path, AtomicReference<ByteBuffer> refbb) {
         super(path);
         this.refbb = refbb;
-        Optional.ofNullable(refbb).map(r -> r.get()).ifPresent(this::setByteBuffer);
+        Optional.ofNullable(refbb).map(AtomicReference::get).ifPresent(this::setByteBuffer);
     }
 
     @Override
-    protected void setLength(long length) throws IOException {
+    protected void setLength(long length) {
         if (length < 0 || length > Integer.MAX_VALUE) {
             throw new IllegalArgumentException("Illegal length: " + length);
         }
@@ -34,7 +33,7 @@ public class RrdMemoryBackend extends ByteBufferBackend {
     }
 
     @Override
-    public long getLength() throws IOException {
+    public long getLength() {
         return Optional.ofNullable(refbb.get()).map(ByteBuffer::capacity).orElse(0);
     }
 
@@ -42,10 +41,9 @@ public class RrdMemoryBackend extends ByteBufferBackend {
      * This method is required by the base class definition, but it does not
      * releases any memory resources at all.
      *
-     * @throws java.io.IOException if any.
      */
     @Override
-    protected void close() throws IOException {
+    protected void close() {
         // Don't release ressources, as backend are cached by the factory and reused
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdMemoryBackendFactory.java

@@ -1,6 +1,5 @@
 package org.rrd4j.core;
 
-import java.io.IOException;
 import java.net.URI;
 import java.nio.ByteBuffer;
 import java.util.Map;
@@ -28,8 +27,8 @@ public class RrdMemoryBackendFactory extends RrdBackendFactory {
      *
      * Creates RrdMemoryBackend object.
      */
-    protected RrdBackend open(String id, boolean readOnly) throws IOException {
-        AtomicReference<ByteBuffer> refbb = backends.computeIfAbsent(id, i -> new AtomicReference<ByteBuffer>());
+    protected RrdBackend open(String id, boolean readOnly) {
+        AtomicReference<ByteBuffer> refbb = backends.computeIfAbsent(id, i -> new AtomicReference<>());
         return new RrdMemoryBackend(id, refbb);
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdNioBackend.java

@@ -29,7 +29,7 @@ public class RrdNioBackend extends ByteBufferBackend implements RrdFileBackend {
     private static final Object unsafe;
     static {
         // Temporary variable, because destinations variables are final
-        // And it interfere with exceptions
+        // And it interferes with exceptions
         Method cleanerMethodTemp;
         Method cleanMethodTemp;
         Method invokeCleanerTemp;
@@ -99,11 +99,7 @@ public class RrdNioBackend extends ByteBufferBackend implements RrdFileBackend {
         }
         try {
             if (!readOnly && threadPool != null) {
-                Runnable syncRunnable = new Runnable() {
-                    public void run() {
-                        sync();
-                    }
-                };
+                Runnable syncRunnable = this::sync;
                 syncRunnableHandle = threadPool.scheduleWithFixedDelay(syncRunnable, syncPeriod, syncPeriod, TimeUnit.SECONDS);
             }
         } catch (RuntimeException rte) {
@@ -193,7 +189,7 @@ public class RrdNioBackend extends ByteBufferBackend implements RrdFileBackend {
     }
 
     @Override
-    public String getCanonicalPath() throws IOException {
+    public String getCanonicalPath() {
         return Paths.get(getPath()).toAbsolutePath().normalize().toString();
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdNioBackendFactory.java

@@ -171,7 +171,7 @@ public class RrdNioBackendFactory extends RrdFileBackendFactory {
     }
 
     @Override
-    public void close() throws IOException {
+    public void close() {
         if (syncThreadPool != null) {
             syncThreadPool.shutdown();
         }

apps/jrobin/java/src/org/rrd4j/core/RrdPrimitive.java

@@ -7,16 +7,16 @@ abstract class RrdPrimitive<U extends RrdUpdater<U>> {
     static final int RRD_INT = 0, RRD_LONG = 1, RRD_DOUBLE = 2, RRD_STRING = 3;
     static final int[] RRD_PRIM_SIZES = {4, 8, 8, 2 * STRING_LENGTH};
 
-    private RrdBackend backend;
-    private int byteCount;
+    private final RrdBackend backend;
+    private final int byteCount;
     private final long pointer;
     private final boolean cachingAllowed;
 
-    RrdPrimitive(RrdUpdater<U> updater, int type, boolean isConstant) throws IOException {
+    RrdPrimitive(RrdUpdater<U> updater, int type, boolean isConstant) {
         this(updater, type, 1, isConstant);
     }
 
-    RrdPrimitive(RrdUpdater<U> updater, int type, int count, boolean isConstant) throws IOException {
+    RrdPrimitive(RrdUpdater<U> updater, int type, int count, boolean isConstant) {
         this.backend = updater.getRrdBackend();
         this.byteCount = RRD_PRIM_SIZES[type] * count;
         this.pointer = updater.getRrdAllocator().allocate(byteCount);

apps/jrobin/java/src/org/rrd4j/core/RrdRandomAccessFileBackend.java

@@ -63,7 +63,7 @@ public class RrdRandomAccessFileBackend extends RrdBackend implements RrdFileBac
     }
 
     @Override
-    public String getCanonicalPath() throws IOException {
+    public String getCanonicalPath() {
         return Paths.get(getPath()).toAbsolutePath().normalize().toString();
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdString.java

@@ -5,11 +5,11 @@ import java.io.IOException;
 class RrdString<U extends RrdUpdater<U>> extends RrdPrimitive<U> {
     private String cache;
 
-    RrdString(RrdUpdater<U> updater, boolean isConstant) throws IOException {
+    RrdString(RrdUpdater<U> updater, boolean isConstant) {
         super(updater, RrdPrimitive.RRD_STRING, isConstant);
     }
 
-    RrdString(RrdUpdater<U> updater) throws IOException {
+    RrdString(RrdUpdater<U> updater) {
         this(updater, false);
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdToolReader.java

@@ -29,7 +29,7 @@ class RrdToolReader extends DataImporter {
         return rrd.getHeader().getDSCount();
     }
 
-    public int getArcCount() throws IOException {
+    public int getArcCount() {
         return rrd.getNumArchives();
     }
 
@@ -38,7 +38,7 @@ class RrdToolReader extends DataImporter {
     }
 
     @Override
-    public DsType getDsType(int dsIndex) throws IOException {
+    public DsType getDsType(int dsIndex) {
         return rrd.getDataSource(dsIndex).getType().getDsType();
     }
 
@@ -79,19 +79,19 @@ class RrdToolReader extends DataImporter {
         return rrd.getArchive(arcIndex).getPdpCount();
     }
 
-    public int getRows(int arcIndex) throws IOException {
+    public int getRows(int arcIndex) {
         return rrd.getArchive(arcIndex).getRowCount();
     }
 
-    public double getStateAccumValue(int arcIndex, int dsIndex) throws IOException {
+    public double getStateAccumValue(int arcIndex, int dsIndex) {
         return rrd.getArchive(arcIndex).getCDPStatusBlock(dsIndex).getValue();
     }
 
-    public int getStateNanSteps(int arcIndex, int dsIndex) throws IOException {
+    public int getStateNanSteps(int arcIndex, int dsIndex) {
         return rrd.getArchive(arcIndex).getCDPStatusBlock(dsIndex).getUnknownDatapoints();
     }
 
-    public double[] getValues(int arcIndex, int dsIndex) throws IOException {
+    public double[] getValues(int arcIndex, int dsIndex) {
         return rrd.getArchive(arcIndex).getValues()[dsIndex];
     }
 

apps/jrobin/java/src/org/rrd4j/core/RrdToolkit.java

@@ -540,7 +540,7 @@ public class RrdToolkit {
         }
         List<String> fileList = new LinkedList<>();
         traverseDirectory(new File(directory), extension, resursive, fileList);
-        String[] result = fileList.toArray(new String[fileList.size()]);
+        String[] result = fileList.toArray(new String[0]);
         Arrays.sort(result);
         return result;
     }

apps/jrobin/java/src/org/rrd4j/core/Util.java

@@ -54,15 +54,12 @@ public class Util {
     // directory under $USER_HOME used for demo graphs storing
     static final String RRD4J_DIR = "rrd4j-demo";
 
-    static final ThreadLocal<NumberFormat> df = new ThreadLocal<NumberFormat>() {
-        @Override
-        protected NumberFormat initialValue() {
-            DecimalFormat ldf = (DecimalFormat) NumberFormat.getNumberInstance(Locale.ENGLISH);
-            ldf.applyPattern(PATTERN);
-            ldf.setPositivePrefix("+");
-            return ldf;
-        }
-    };
+    static final ThreadLocal<NumberFormat> df = ThreadLocal.withInitial(() -> {
+        DecimalFormat ldf = (DecimalFormat) NumberFormat.getNumberInstance(Locale.ENGLISH);
+        ldf.applyPattern(PATTERN);
+        ldf.setPositivePrefix("+");
+        return ldf;
+    });
 
     private static final Pattern SPRINTF_PATTERN = Pattern.compile("([^%]|^)%([^a-zA-Z%]*)l(f|g|e)");
 

apps/jrobin/java/src/org/rrd4j/core/XmlReader.java

@@ -11,8 +11,9 @@ import java.util.Locale;
 
 class XmlReader extends DataImporter {
 
-    private Element root;
-    private Node[] dsNodes, arcNodes;
+    private final Element root;
+    private final Node[] dsNodes;
+    private final Node[] arcNodes;
 
     XmlReader(String xmlFilePath) throws IOException {
         root = Util.Xml.getRootElement(new File(xmlFilePath));

apps/jrobin/java/src/org/rrd4j/core/XmlTemplate.java

@@ -24,8 +24,8 @@ public abstract class XmlTemplate {
     private static final Pattern PATTERN = Pattern.compile(PATTERN_STRING);
 
     protected Element root;
-    private HashMap<String, Object> valueMap = new HashMap<>();
-    private HashSet<Node> validatedNodes = new HashSet<>();
+    private final HashMap<String, Object> valueMap = new HashMap<>();
+    private final HashSet<Node> validatedNodes = new HashSet<>();
 
     /**
      * <p>Constructor for XmlTemplate.</p>
@@ -85,7 +85,7 @@ public abstract class XmlTemplate {
      * @param value value to be set in the XML template
      */
     public void setVariable(String name, int value) {
-        valueMap.put(name, Integer.valueOf(value));
+        valueMap.put(name, value);
     }
 
     /**
@@ -97,7 +97,7 @@ public abstract class XmlTemplate {
      * @param value value to be set in the XML template
      */
     public void setVariable(String name, long value) {
-        valueMap.put(name, Long.valueOf(value));
+        valueMap.put(name, value);
     }
 
     /**
@@ -109,7 +109,7 @@ public abstract class XmlTemplate {
      * @param value value to be set in the XML template
      */
     public void setVariable(String name, double value) {
-        valueMap.put(name, Double.valueOf(value));
+        valueMap.put(name, value);
     }
 
     /**
@@ -185,7 +185,7 @@ public abstract class XmlTemplate {
     /**
      * Returns the list of variables that should be set in this template.
      *
-     * @return List of variable names as an array of strings.
+     * @return Array of variable names as an array of strings.
      */
     public String[] getVariables() {
         ArrayList<String> list = new ArrayList<>();
@@ -198,7 +198,7 @@ public abstract class XmlTemplate {
             }
         }
 
-        return list.toArray(new String[list.size()]);
+        return list.toArray(new String[0]);
     }
 
     /**
@@ -301,7 +301,7 @@ public abstract class XmlTemplate {
             String var = matcher.group(1);
             if (valueMap.containsKey(var)) {
                 // mapping found
-                result.append(templateValue.substring(lastMatchEnd, matcher.start()));
+                result.append(templateValue, lastMatchEnd, matcher.start());
                 result.append(valueMap.get(var).toString());
                 lastMatchEnd = matcher.end();
             }

apps/jrobin/java/src/org/rrd4j/core/XmlWriter.java

@@ -24,7 +24,7 @@ public class XmlWriter implements AutoCloseable {
     }
 
     private final PrintWriter writer;
-    private final StringBuilder indent = new StringBuilder("");
+    private final StringBuilder indent = new StringBuilder();
     private final Deque<String> openTags = new LinkedList<>();
 
     /**

apps/jrobin/java/src/org/rrd4j/core/jrrd/Archive.java

@@ -1,6 +1,5 @@
 package org.rrd4j.core.jrrd;
 
-import java.io.IOException;
 import java.io.PrintStream;
 import java.text.DecimalFormat;
 import java.text.DecimalFormatSymbols;
@@ -21,7 +20,7 @@ import java.util.Locale;
  */
 public class Archive {
 
-    private static enum rra_par_en {RRA_cdp_xff_val, RRA_hw_alpha};
+    private enum rra_par_en {RRA_cdp_xff_val, RRA_hw_alpha}
 
     final RRDatabase db;
     /** Header offset within file in bytes */
@@ -47,7 +46,7 @@ public class Archive {
     /** Cached content */
     private double[][] values;
 
-    Archive(RRDatabase db) throws IOException {
+    Archive(RRDatabase db) {
 
         this.db = db;
 
@@ -74,9 +73,9 @@ public class Archive {
         return type;
     }
 
-    void loadCDPStatusBlocks(RRDFile file, int numBlocks) throws IOException {
+    void loadCDPStatusBlocks(RRDFile file, int numBlocks) {
 
-        cdpStatusBlocks = new ArrayList<CDPStatusBlock>();
+        cdpStatusBlocks = new ArrayList<>();
 
         for (int i = 0; i < numBlocks; i++) {
             cdpStatusBlocks.add(new CDPStatusBlock(file));
@@ -103,11 +102,11 @@ public class Archive {
         return cdpStatusBlocks.iterator();
     }
 
-    void loadCurrentRow(RRDFile file) throws IOException {
+    void loadCurrentRow(RRDFile file) {
         currentRow = file.readLong();
     }
 
-    void loadData(RRDFile file, int dsCount) throws IOException {
+    void loadData(RRDFile file, int dsCount) {
 
         dataOffset = file.getFilePointer();
 
@@ -115,8 +114,7 @@ public class Archive {
         file.skipBytes(Constants.SIZE_OF_DOUBLE * rowCount * dsCount);
     }
 
-    void loadData(DataChunk chunk)
-            throws IOException {
+    void loadData(DataChunk chunk) {
 
         long rowIndexPointer;
 
@@ -186,18 +184,14 @@ public class Archive {
 
         int cdpIndex = 0;
 
-        for (Iterator<CDPStatusBlock> i = cdpStatusBlocks.iterator(); i.hasNext();) {
-            CDPStatusBlock cdp = i.next();
-
+        for (CDPStatusBlock cdp : cdpStatusBlocks) {
             s.print(sb);
             s.print(cdpIndex);
             s.print("].value = ");
 
             double value = cdp.value;
 
-            s.println(Double.isNaN(value)
-                    ? "NaN"
-                            : numberFormat.format(value));
+            s.println(Double.isNaN(value) ? "NaN" : numberFormat.format(value));
             s.print(sb);
             s.print(cdpIndex++);
             s.print("].unknown_datapoints = ");
@@ -206,97 +200,89 @@ public class Archive {
     }
 
     void toXml(PrintStream s) {
+        s.println("\t<rra>");
+        s.print("\t\t<cf> ");
+        s.print(type);
+        s.println(" </cf>");
+        s.print("\t\t<pdp_per_row> ");
+        s.print(pdpCount);
+        s.print(" </pdp_per_row> <!-- ");
+        s.print(db.header.pdpStep * pdpCount);
+        s.println(" seconds -->");
+        s.print("\t\t<xff> ");
+        s.print(xff);
+        s.println(" </xff>");
+        s.println();
+        s.println("\t\t<cdp_prep>");
 
-        try {
-            s.println("\t<rra>");
-            s.print("\t\t<cf> ");
-            s.print(type);
-            s.println(" </cf>");
-            s.print("\t\t<pdp_per_row> ");
-            s.print(pdpCount);
-            s.print(" </pdp_per_row> <!-- ");
-            s.print(db.header.pdpStep * pdpCount);
-            s.println(" seconds -->");
-            s.print("\t\t<xff> ");
-            s.print(xff);
-            s.println(" </xff>");
-            s.println();
-            s.println("\t\t<cdp_prep>");
+        for (CDPStatusBlock cdpStatusBlock : cdpStatusBlocks) {
+            cdpStatusBlock.toXml(s);
+        }
 
-            for (int i = 0; i < cdpStatusBlocks.size(); i++) {
-                cdpStatusBlocks.get(i).toXml(s);
+        s.println("\t\t</cdp_prep>");
+        s.println("\t\t<database>");
+
+        long timer = -(rowCount - 1);
+        int counter = 0;
+        int row = currentRow;
+
+        db.rrdFile.seek(dataOffset + (row + 1) * db.header.dsCount * Constants.SIZE_OF_DOUBLE);
+
+        long lastUpdate = db.lastUpdate.getTime() / 1000;
+        int pdpStep = db.header.pdpStep;
+        NumberFormat numberFormat = new DecimalFormat("0.0000000000E0", DecimalFormatSymbols.getInstance(Locale.US));
+        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z");
+
+        while (counter++ < rowCount) {
+            row++;
+
+            if (row == rowCount) {
+                row = 0;
+
+                db.rrdFile.seek(dataOffset);
             }
 
-            s.println("\t\t</cdp_prep>");
-            s.println("\t\t<database>");
+            long now = (lastUpdate - lastUpdate % (pdpCount * pdpStep))
+                    + (timer * pdpCount * pdpStep);
 
-            long timer = -(rowCount - 1);
-            int counter = 0;
-            int row = currentRow;
+            timer++;
 
-            db.rrdFile.seek(dataOffset + (row + 1) * db.header.dsCount * Constants.SIZE_OF_DOUBLE);
+            s.print("\t\t\t<!-- ");
+            s.print(dateFormat.format(new Date(now * 1000)));
+            s.print(" / ");
+            s.print(now);
+            s.print(" --> ");
 
-            long lastUpdate = db.lastUpdate.getTime() / 1000;
-            int pdpStep = db.header.pdpStep;
-            NumberFormat numberFormat = new DecimalFormat("0.0000000000E0", DecimalFormatSymbols.getInstance(Locale.US));
-            SimpleDateFormat dateFormat =
-                    new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z");
+            s.println("<row>");
+            for (int col = 0; col < db.header.dsCount; col++) {
+                s.print("<v> ");
 
-            while (counter++ < rowCount) {
-                row++;
+                double value = db.rrdFile.readDouble();
 
-                if (row == rowCount) {
-                    row = 0;
-
-                    db.rrdFile.seek(dataOffset);
+                // NumberFormat doesn't know how to handle NaN
+                if (Double.isNaN(value)) {
+                    s.print("NaN");
+                }
+                else {
+                    s.print(numberFormat.format(value));
                 }
 
-                long now = (lastUpdate - lastUpdate % (pdpCount * pdpStep))
-                        + (timer * pdpCount * pdpStep);
-
-                timer++;
-
-                s.print("\t\t\t<!-- ");
-                s.print(dateFormat.format(new Date(now * 1000)));
-                s.print(" / ");
-                s.print(now);
-                s.print(" --> ");
-
-                s.println("<row>");
-                for (int col = 0; col < db.header.dsCount; col++) {
-                    s.print("<v> ");
-
-                    double value = db.rrdFile.readDouble();
-
-                    // NumberFormat doesn't know how to handle NaN
-                    if (Double.isNaN(value)) {
-                        s.print("NaN");
-                    }
-                    else {
-                        s.print(numberFormat.format(value));
-                    }
-
-                    s.print(" </v>");
-                }
-
-                s.println("</row>");
+                s.print(" </v>");
             }
 
-            s.println("\t\t</database>");
-            s.println("\t</rra>");
-        }
-        catch (IOException e) {    // Is the best thing to do here?
-            throw new RuntimeException(e.getMessage());
+            s.println("</row>");
         }
+
+        s.println("\t\t</database>");
+        s.println("\t</rra>");
     }
 
     /**
      * <p>Getter for the field <code>values</code>.</p>
      *
      * @return an array of double.
-     * @throws java.io.IOException if any.
      */
-    public double[][] getValues() throws IOException {
+    public double[][] getValues() {
         if (values != null) {
             return values;
         }

apps/jrobin/java/src/org/rrd4j/core/jrrd/CDPStatusBlock.java

@@ -1,6 +1,5 @@
 package org.rrd4j.core.jrrd;
 
-import java.io.IOException;
 import java.io.PrintStream;
 
 /**
@@ -11,7 +10,7 @@ import java.io.PrintStream;
  */
 public class CDPStatusBlock {
 
-    private static enum cdp_par_en {
+    private enum cdp_par_en {
         CDP_val, CDP_unkn_pdp_cnt, CDP_hw_intercept, CDP_hw_last_intercept, CDP_hw_slope, 
         CDP_hw_last_slope, CDP_null_count,
         CDP_last_null_count, CDP_primary_val, CDP_secondary_val
@@ -27,7 +26,7 @@ public class CDPStatusBlock {
     final double secondary_value;
     final double primary_value;
 
-    CDPStatusBlock(RRDFile file) throws IOException {
+    CDPStatusBlock(RRDFile file) {
         //Should read MAX_CDP_PAR_EN = 10
         //Size should be 0x50
         offset = file.getFilePointer();

apps/jrobin/java/src/org/rrd4j/core/jrrd/Constants.java

@@ -2,25 +2,25 @@ package org.rrd4j.core.jrrd;
 
 interface Constants {
     /** Constant <code>DS_NAM_SIZE=20</code> */
-    final int DS_NAM_SIZE = 20;
+    int DS_NAM_SIZE = 20;
     /** Constant <code>DST_SIZE=20</code> */
-    final int DST_SIZE = 20;
+    int DST_SIZE = 20;
     /** Constant <code>CF_NAM_SIZE=20</code> */
-    final int CF_NAM_SIZE = 20;
+    int CF_NAM_SIZE = 20;
     /** Constant <code>LAST_DS_LEN=30</code> */
-    final  int LAST_DS_LEN = 30;
+    int LAST_DS_LEN = 30;
     /** Constant <code>COOKIE="RRD"</code> */
-    static final String COOKIE = "RRD";
+    String COOKIE = "RRD";
     /** Constant <code>MAX_SUPPORTED_VERSION=3</code> */
-    public static final int MAX_SUPPORTED_VERSION = 3;
+    int MAX_SUPPORTED_VERSION = 3;
     /** Constant <code>UNDEFINED_VERSION="UNDEF"</code> */
-    public static final String UNDEFINED_VERSION = "UNDEF";
+    String UNDEFINED_VERSION = "UNDEF";
     /** Constant <code>UNDEFINED_VERSION_AS_INT=-1</code> */
-    public static final int UNDEFINED_VERSION_AS_INT = -1;
+    int UNDEFINED_VERSION_AS_INT = -1;
     /** Constant <code>VERSION_WITH_LAST_UPDATE_SEC=3</code> */
-    public static int VERSION_WITH_LAST_UPDATE_SEC = 3;
+    int VERSION_WITH_LAST_UPDATE_SEC = 3;
     /** Constant <code>FLOAT_COOKIE=8.642135E130</code> */
-    static final double FLOAT_COOKIE = 8.642135E130;
+    double FLOAT_COOKIE = 8.642135E130;
     /** Constant <code>SIZE_OF_DOUBLE=8</code> */
-    public static final int SIZE_OF_DOUBLE = 8;
+    int SIZE_OF_DOUBLE = 8;
 }

apps/jrobin/java/src/org/rrd4j/core/jrrd/DataSource.java

@@ -1,6 +1,5 @@
 package org.rrd4j.core.jrrd;
 
-import java.io.IOException;
 import java.io.PrintStream;
 import java.text.NumberFormat;
 
@@ -12,7 +11,7 @@ import java.text.NumberFormat;
  */
 public class DataSource {
 
-    private static enum ds_param_en { DS_mrhb_cnt, DS_min_val, DS_max_val, DS_cde }
+    private enum ds_param_en { DS_mrhb_cnt, DS_min_val, DS_max_val, DS_cde }
 
     private final long offset;
     private final long size;
@@ -24,7 +23,7 @@ public class DataSource {
     // initialized during RRDatabase construction
     private PDPStatusBlock pdpStatusBlock;
 
-    DataSource(RRDFile file) throws IOException {
+    DataSource(RRDFile file) {
 
         offset = file.getFilePointer();
         name = file.readString(Constants.DS_NAM_SIZE);
@@ -37,7 +36,7 @@ public class DataSource {
         size = file.getFilePointer() - offset;
     }
 
-    void loadPDPStatusBlock(RRDFile file) throws IOException {
+    void loadPDPStatusBlock(RRDFile file) {
         pdpStatusBlock = new PDPStatusBlock(file);
     }
 

apps/jrobin/java/src/org/rrd4j/core/jrrd/PDPStatusBlock.java

@@ -1,7 +1,5 @@
 package org.rrd4j.core.jrrd;
 
-import java.io.IOException;
-
 /**
  * Instances of this class model the primary data point status from an RRD file.
  *
@@ -10,14 +8,14 @@ import java.io.IOException;
  */
 public class PDPStatusBlock {
 
-    private long offset;
-    private long size;
-    String lastReading;
-    int unknownSeconds;
-    double value;
-    private static enum pdp_par_en {PDP_unkn_sec_cnt, PDP_val};
+    private final long offset;
+    private final long size;
+    final String lastReading;
+    final int unknownSeconds;
+    final double value;
+    private enum pdp_par_en {PDP_unkn_sec_cnt, PDP_val}
 
-    PDPStatusBlock(RRDFile file) throws IOException {
+    PDPStatusBlock(RRDFile file) {
 
         offset = file.getFilePointer();
         lastReading = file.readString(Constants.LAST_DS_LEN);

apps/jrobin/java/src/org/rrd4j/core/jrrd/RRDFile.java

@@ -64,7 +64,7 @@ class RRDFile implements Constants {
             if (!ok) {
                 try {
                     close();
-                } catch (Throwable ignored) {
+                } catch (IOException ignored) {
                 }
                 // and then rethrow
             }
@@ -134,15 +134,15 @@ class RRDFile implements Constants {
         return alignment;
     }
 
-    double readDouble() throws IOException {
+    double readDouble() {
         return mappedByteBuffer.getDouble();
     }
 
-    int readInt() throws IOException {
+    int readInt() {
         return mappedByteBuffer.getInt();
     }
 
-    int readLong() throws IOException {
+    int readLong() {
         if(longSize == 4) {
             return mappedByteBuffer.getInt();
         }
@@ -151,20 +151,20 @@ class RRDFile implements Constants {
         }
     }
 
-    String readString(int maxLength) throws IOException {
+    String readString(int maxLength) {
         byte[] array = new byte[maxLength];
         mappedByteBuffer.get(array);
 
         return new String(array, 0, maxLength).trim();
     }
 
-    void skipBytes(int n) throws IOException {
+    void skipBytes(int n) {
         mappedByteBuffer.position(mappedByteBuffer.position() + n);
     }
 
-    int align(int boundary) throws IOException {
+    int align(int boundary) {
 
-        int skip = (int) (boundary - (mappedByteBuffer.position() % boundary)) % boundary;
+        int skip = (boundary - (mappedByteBuffer.position() % boundary)) % boundary;
 
         if (skip != 0) {
             mappedByteBuffer.position(mappedByteBuffer.position() + skip);
@@ -173,15 +173,15 @@ class RRDFile implements Constants {
         return skip;
     }
 
-    int align() throws IOException {
+    int align() {
         return align(alignment);
     }
 
-    long info() throws IOException {
+    long info() {
         return mappedByteBuffer.position();
     }
 
-    long getFilePointer() throws IOException {
+    long getFilePointer() {
         return mappedByteBuffer.position();
     }
 
@@ -191,13 +191,13 @@ class RRDFile implements Constants {
         }
     }
 
-    void read(ByteBuffer bb) throws IOException{
+    void read(ByteBuffer bb) {
         int count = bb.remaining();
         bb.put((ByteBuffer) mappedByteBuffer.duplicate().limit(mappedByteBuffer.position() + count));
         mappedByteBuffer.position(mappedByteBuffer.position() + count);
     }
 
-    UnivalArray getUnivalArray(int size) throws IOException {
+    UnivalArray getUnivalArray(int size) {
         return new UnivalArray(this, size);
     }
 

apps/jrobin/java/src/org/rrd4j/core/jrrd/RRDatabase.java

@@ -63,10 +63,10 @@ public class RRDatabase implements Closeable {
         rrdFile = new RRDFile(file);
         header = new Header(rrdFile);
 
-        nameindex = new HashMap<String, Integer>(header.dsCount);
+        nameindex = new HashMap<>(header.dsCount);
 
         // Load the data sources
-        dataSources = new ArrayList<DataSource>(header.dsCount);
+        dataSources = new ArrayList<>(header.dsCount);
 
         for (int i = 0; i < header.dsCount; i++) {
             DataSource ds = new DataSource(rrdFile);
@@ -75,7 +75,7 @@ public class RRDatabase implements Closeable {
         }
 
         // Load the archives
-        archives = new ArrayList<Archive>(header.rraCount);
+        archives = new ArrayList<>(header.rraCount);
 
         for (int i = 0; i < header.rraCount; i++) {
             Archive archive = new Archive(this);
@@ -214,7 +214,7 @@ public class RRDatabase implements Closeable {
 
     ArrayList<Archive> getArchiveList(ConsolidationFunctionType type) {
 
-        ArrayList<Archive> subset = new ArrayList<Archive>();
+        ArrayList<Archive> subset = new ArrayList<>();
 
         for (Archive archive : archives) {
             if (archive.getType().equals(type)) {
@@ -449,7 +449,7 @@ public class RRDatabase implements Closeable {
      * Outputs the content of the database to the given print stream
      * as a stream of XML. The XML format is almost identical to that produced by
      * <a href="http://people.ee.ethz.ch/~oetiker/webtools/rrdtool/manual/rrddump.html">rrdtool dump</a>
-     * 
+     * <p>
      * A flush is issued at the end of the XML generation, so auto flush of the PrintStream can be set to false
      *
      * @param s the PrintStream to send the XML to.
@@ -470,7 +470,7 @@ public class RRDatabase implements Closeable {
         s.print("\t<lastupdate> ");
         s.print(lastUpdate.getTime() / 1000);
         s.print(" </lastupdate> <!-- ");
-        s.print(lastUpdate.toString());
+        s.print(lastUpdate);
         s.println(" -->");
         s.println();
 

apps/jrobin/java/src/org/rrd4j/core/jrrd/UnivalArray.java

@@ -1,6 +1,5 @@
 package org.rrd4j.core.jrrd;
 
-import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 
@@ -19,9 +18,8 @@ class UnivalArray {
      *
      * @param file the RRdFile
      * @param size the numer of elements in the array
-     * @throws java.io.IOException if any.
      */
-    public UnivalArray(RRDFile file, int size) throws IOException {
+    public UnivalArray(RRDFile file, int size) {
         sizeoflong = file.getBits();
         buffer = ByteBuffer.allocate(size * 8);
         if(file.isBigEndian())

apps/jrobin/java/src/org/rrd4j/core/timespec/Epoch.java

@@ -4,8 +4,6 @@ import org.rrd4j.core.Util;
 
 import javax.swing.*;
 import java.awt.*;
-import java.awt.event.ActionEvent;
-import java.awt.event.ActionListener;
 import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.Date;
@@ -44,12 +42,6 @@ public class Epoch extends JFrame {
     private final SimpleDateFormat[] parsers = new SimpleDateFormat[supportedFormats.length];
     private final String helpText;
 
-    private final Timer timer = new Timer(1000, new ActionListener() {
-        public void actionPerformed(ActionEvent e) {
-            showTimestamp();
-        }
-    });
-
     private final JLabel topLabel = new JLabel("Enter timestamp or readable date:");
     private final JTextField inputField = new JTextField(25);
     private final JButton convertButton = new JButton("Convert");
@@ -73,6 +65,7 @@ public class Epoch extends JFrame {
         tooltipBuff.append("Copyright (c) 2013-2020 The RRD4J Authors. Copyright (c) 2001-2005 Sasa Markovic and Ciaran Treanor. Copyright (c) 2013 The OpenNMS Group, Inc. Licensed under the Apache License, Version 2.0.</html>");
         helpText = tooltipBuff.toString();
         constructUI();
+        Timer timer = new Timer(1000, e -> showTimestamp());
         timer.start();
     }
 
@@ -83,17 +76,10 @@ public class Epoch extends JFrame {
         c.add(inputField, BorderLayout.WEST);
         c.add(convertButton, BorderLayout.CENTER);
         convertButton.setToolTipText(helpText);
-        convertButton.addActionListener(new ActionListener() {
-            public void actionPerformed(ActionEvent e) {
-                convert();
-            }
-        });
+        convertButton.addActionListener(e -> convert());
         c.add(helpButton, BorderLayout.EAST);
-        helpButton.addActionListener(new ActionListener() {
-            public void actionPerformed(ActionEvent e) {
-                JOptionPane.showMessageDialog(helpButton, helpText, "Epoch Help", JOptionPane.INFORMATION_MESSAGE);
-            }
-        });
+        helpButton.addActionListener(
+                e -> JOptionPane.showMessageDialog(helpButton, helpText, "Epoch Help", JOptionPane.INFORMATION_MESSAGE));
         inputField.requestFocus();
         getRootPane().setDefaultButton(convertButton);
         setResizable(false);

apps/jrobin/java/src/org/rrd4j/core/timespec/TimeParser.java

@@ -6,7 +6,7 @@ import java.time.Instant;
  * Class which parses at-style time specification (described in detail on the rrdfetch man page),
  * used in all RRDTool commands. This code is in most parts just a java port of Tobi's parsetime.c
  * code.
- * 
+ * <p>
  * For years written with two digits, any year before 38 will be post 2000.
  *
  */
@@ -14,8 +14,8 @@ public class TimeParser {
     private static final int PREVIOUS_OP = -1;
 
     TimeToken token;
-    TimeScanner scanner;
-    TimeSpec spec;
+    final TimeScanner scanner;
+    final TimeSpec spec;
 
     int op = TimeToken.PLUS;
     int prev_multiplier = -1;
@@ -104,7 +104,7 @@ public class TimeParser {
      * the scanner state to what it was at entry, and returns without setting anything.
      */
     private void timeOfDay() {
-        int hour = 0;
+        int hour;
         int minute = 0;
         /* save token status in case we must abort */
         scanner.saveState();
@@ -183,8 +183,8 @@ public class TimeParser {
 
     private void day() {
         long mday = 0;
-        long wday = 0;
-        long mon = 0;
+        long wday;
+        long mon;
         long year = spec.year;
         switch (token.token_id) {
         case TimeToken.YESTERDAY:

apps/jrobin/java/src/org/rrd4j/core/timespec/TimeScanner.java

@@ -1,7 +1,7 @@
 package org.rrd4j.core.timespec;
 
 class TimeScanner {
-    private String dateString;
+    private final String dateString;
 
     private int pos, pos_save;
     private TimeToken token, token_save;
@@ -108,7 +108,7 @@ class TimeScanner {
     }
 
     TimeToken nextToken() {
-        StringBuilder buffer = new StringBuilder("");
+        StringBuilder buffer = new StringBuilder();
         while (pos < dateString.length()) {
             char c = dateString.charAt(pos++);
             if (Character.isWhitespace(c) || c == '_' || c == ',') {

apps/jrobin/java/src/org/rrd4j/core/timespec/TimeSpec.java

@@ -20,7 +20,7 @@ public class TimeSpec {
     int wday;
     int dyear, dmonth, dday, dhour, dmin, dsec;
 
-    String dateString;
+    final String dateString;
 
     TimeSpec context;
 
@@ -135,4 +135,3 @@ public class TimeSpec {
         };
     }
 }
-

apps/jrobin/java/src/org/rrd4j/data/Aggregates.java

@@ -107,7 +107,7 @@ public class Aggregates {
     public String dump() {
         StringBuilder bl = new StringBuilder();
         for(ConsolFun cf: ConsolFun.values()) {
-            bl.append(cf.name() + '=' + Util.formatDouble(this.getAggregate(cf)));
+            bl.append(cf.name()).append('=').append(Util.formatDouble(this.getAggregate(cf)));
         }
         return bl.toString();
     }

apps/jrobin/java/src/org/rrd4j/data/Aggregator.java

@@ -5,7 +5,8 @@ import java.util.Arrays;
 import java.util.List;
 
 class Aggregator {
-    private final long timestamps[], step;
+    private final long[] timestamps;
+    private final long step;
     private final double[] values;
 
     Aggregator(long[] timestamps, double[] values) {
@@ -60,13 +61,13 @@ class Aggregator {
     }
 
     double getPercentile(long tStart, long tEnd, double percentile) {
-        List<Double> valueList = new ArrayList<Double>();
+        List<Double> valueList = new ArrayList<>();
         // create a list of included datasource values (different from NaN)
         for (int i = 0; i < timestamps.length; i++) {
             long left = Math.max(timestamps[i] - step, tStart);
             long right = Math.min(timestamps[i], tEnd);
             if (right > left && !Double.isNaN(values[i])) {
-                valueList.add(Double.valueOf(values[i]));
+                valueList.add(values[i]);
             }
         }
         // create an array to work with
@@ -74,7 +75,7 @@ class Aggregator {
         if (count > 1) {
             double[] valuesCopy = new double[count];
             for (int i = 0; i < count; i++) {
-                valuesCopy[i] = valueList.get(i).doubleValue();
+                valuesCopy[i] = valueList.get(i);
             }
             // sort array
             Arrays.sort(valuesCopy);
@@ -90,4 +91,3 @@ class Aggregator {
         return Double.NaN;
     }
 }
-

apps/jrobin/java/src/org/rrd4j/data/CubicSplineInterpolator.java

@@ -15,8 +15,8 @@ import java.util.Date;
  */
 @SuppressWarnings("deprecation")
 public class CubicSplineInterpolator extends Plottable {
-    private double[] x;
-    private double[] y;
+    private final double[] x;
+    private final double[] y;
 
     // second derivates come here
     private double[] y2;
@@ -104,6 +104,7 @@ public class CubicSplineInterpolator extends Plottable {
         for (int i = 0; i < x.length - 1 && ok; i++) {
             if (x[i] >= x[i + 1] || Double.isNaN(y[i])) {
                 ok = false;
+                break;
             }
         }
         if (!ok) {

apps/jrobin/java/src/org/rrd4j/data/DataProcessor.java

@@ -64,7 +64,7 @@ public class DataProcessor implements DataHolder {
 
     private long tStart;
     private long tEnd;
-    private long timestamps[];
+    private long[] timestamps;
     private long lastRrdArchiveUpdateTime = 0;
     // this will be adjusted later
     private long step = 0;
@@ -74,7 +74,7 @@ public class DataProcessor implements DataHolder {
     private TimeZone tz = TimeZone.getDefault();
 
     // the order is important, ordinary HashMap is unordered
-    private Map<String, Source> sources = new LinkedHashMap<String, Source>();
+    private final Map<String, Source> sources = new LinkedHashMap<>();
 
     private Def[] defSources;
 
@@ -112,7 +112,7 @@ public class DataProcessor implements DataHolder {
      * Creates new DataProcessor object for the given time span. Ending date may be set to null.
      * In that case, the class will try to find optimal ending date based on the last update time of
      * RRD files processed with the {@link #processData()} method.
-     * 
+     * <p>
      * It use the time zone for starting calendar date.
      *
      * @param gc1 Starting Calendar date
@@ -365,7 +365,7 @@ public class DataProcessor implements DataHolder {
 
     /**
      * This method is just an alias for {@link #getPercentile(String)} method.
-     *
+     * <p>
      * Used by ISPs which charge for bandwidth utilization on a "95th percentile" basis.<p>
      *
      * The 95th percentile is the highest source value left when the top 5% of a numerically sorted set
@@ -430,7 +430,7 @@ public class DataProcessor implements DataHolder {
      * @return array of datasource names
      */
     public String[] getSourceNames() {
-        return sources.keySet().toArray(new String[sources.keySet().size()]);
+        return sources.keySet().toArray(new String[0]);
     }
 
     /**
@@ -570,7 +570,7 @@ public class DataProcessor implements DataHolder {
     /**
      * Creates a datasource that performs a percentile calculation on an
      * another named datasource to yield a single value.
-     *
+     * <p>
      * Requires that the other datasource has already been defined; otherwise, it'll
      * end up with no data
      *
@@ -588,7 +588,7 @@ public class DataProcessor implements DataHolder {
     /**
      * Creates a datasource that performs a variable calculation on an
      * another named datasource to yield a single combined timestamp/value.
-     *
+     * <p>
      * Requires that the other datasource has already been defined; otherwise, it'll
      * end up with no data
      *
@@ -606,7 +606,7 @@ public class DataProcessor implements DataHolder {
     /**
      * Creates a datasource that performs a variable calculation on an
      * another named datasource to yield a single combined timestamp/value.
-     *
+     * <p>
      * Requires that the other datasource has already been defined; otherwise, it'll
      * end up with no data
      *
@@ -970,7 +970,7 @@ public class DataProcessor implements DataHolder {
     // PRIVATE METHODS
 
     private void extractDefs() {
-        defSources = sources.values().stream().filter(s -> s instanceof Def).toArray(Def[]::new);
+        defSources = sources.values().stream().filter(Def.class::isInstance).toArray(Def[]::new);
     }
 
     private void fetchRrdData() throws IOException {
@@ -1006,7 +1006,7 @@ public class DataProcessor implements DataHolder {
                 }
                 if (!defSources[i].isLoaded()) {
                     // not fetched yet
-                    Set<String> dsNames = new HashSet<String>();
+                    Set<String> dsNames = new HashSet<>();
                     dsNames.add(defSources[i].getDsName());
                     // look for all other datasources with the same path and the same consolidation function
                     for (int j = i + 1; j < defSources.length; j++) {

apps/jrobin/java/src/org/rrd4j/data/Def.java

@@ -1,6 +1,5 @@
 package org.rrd4j.data;
 
-import java.io.IOException;
 import java.net.URI;
 
 import org.rrd4j.ConsolFun;
@@ -36,7 +35,7 @@ class Def extends Source {
         this.backend = backend;
     }
 
-    URI getCanonicalUri() throws IOException {
+    URI getCanonicalUri() {
        return rrdUri;
     }
 
@@ -52,7 +51,7 @@ class Def extends Source {
         return backend;
     }
 
-    boolean isCompatibleWith(Def def) throws IOException {
+    boolean isCompatibleWith(Def def) {
         return getCanonicalUri().equals(def.getCanonicalUri()) &&
                 getConsolFun() == def.consolFun &&
                 ((backend == null && def.backend == null) ||

apps/jrobin/java/src/org/rrd4j/data/IPlottable.java

@@ -16,5 +16,5 @@ public interface IPlottable {
      * @param timestamp Timestamp in seconds for the datapoint.
      * @return Double value of the datapoint.
      */
-    public double getValue(long timestamp);
+    double getValue(long timestamp);
 }

apps/jrobin/java/src/org/rrd4j/data/LinearInterpolator.java

@@ -48,14 +48,14 @@ public class LinearInterpolator extends Plottable {
         LEFT,
         RIGHT,
         LINEAR,
-        REGRESSION;
+        REGRESSION
     }
 
     private int lastIndexUsed = 0;
     private Method interpolationMethod = Method.LINEAR;
 
-    private long[] timestamps;
-    private double[] values;
+    private final long[] timestamps;
+    private final double[] values;
 
     // used only if INTERPOLATE_BESTFIT is specified
     double b0 = Double.NaN;
@@ -117,6 +117,7 @@ public class LinearInterpolator extends Plottable {
         for (int i = 0; i < timestamps.length - 1 && ok; i++) {
             if (timestamps[i] >= timestamps[i + 1]) {
                 ok = false;
+                break;
             }
         }
         if (!ok) {

apps/jrobin/java/src/org/rrd4j/data/Normalizer.java

@@ -41,7 +41,7 @@ class Normalizer {
                     long t2 = Math.min(rawTimestamps[rawSeg], timestamps[fillSeg]);
                     if (t1 < t2) {
                         values[fillSeg] = Util.sum(values[fillSeg], (t2 - t1) * rawValues[rawSeg]);
-                        weights[fillSeg] = Util.sum(weights[fillSeg], (double)(t2 - t1));
+                        weights[fillSeg] = Util.sum(weights[fillSeg], (t2 - t1));
                     }
                     else {
                         overlap = false;

apps/jrobin/java/src/org/rrd4j/data/RpnCalculator.java

@@ -396,7 +396,7 @@ class RpnCalculator {
             @Override
             void do_method(RpnCalculator c, State s) {
                 TimeZone tz = s.getTimeZone();
-                c.push((double)(c.timestamps[s.slot] + ((long) tz.getOffset(c.timestamps[s.slot]) / 1000D)));
+                c.push(c.timestamps[s.slot] + ((long) tz.getOffset(c.timestamps[s.slot]) / 1000D));
             }
         },
         TKN_YEAR("YEAR") {
@@ -569,7 +569,7 @@ class RpnCalculator {
                 }
 
                 /* the real calculation */
-                double val = Double.NaN;
+                double val;
 
                 /* the info on the datasource */
                 double[] vals = c.dataProcessor.getValues(c.tokens[s.rpi-1].variable);
@@ -615,7 +615,7 @@ class RpnCalculator {
                 val = Double.NaN;
                 if (s.token.id == TKN_PREDICT) {  /* the average */
                     if (count > 0) {
-                        val = sum / (double) count;
+                        val = sum / count;
                     }
                 } else {
                     if (count > 1) { /* the sigma case */
@@ -649,14 +649,14 @@ class RpnCalculator {
     private static final PerfectStringHash perfect;
     static
     {
-        List<String> tokenStrings = new ArrayList<String>(Token_Symbol.values().length);
+        List<String> tokenStrings = new ArrayList<>(Token_Symbol.values().length);
         for(Token_Symbol s: Token_Symbol.values()) {
             if(! s.token_string.isEmpty()) {
                 tokenStrings.add(s.token_string);
             }
         }
 
-        String[] array = tokenStrings.toArray(new String[tokenStrings.size()]);
+        String[] array = tokenStrings.toArray(new String[0]);
         perfect = new PerfectStringHash(array);
         symbols = new Token_Symbol[tokenStrings.size()];
         for(Token_Symbol s: Token_Symbol.values()) {
@@ -683,7 +683,7 @@ class RpnCalculator {
         this.sourceName = sourceName;
         this.dataProcessor = dataProcessor;
         this.timestamps = dataProcessor.getTimestamps();
-        this.timeStep = (double)(timestamps[1] - timestamps[0]);
+        this.timeStep = (timestamps[1] - timestamps[0]);
         this.calculatedValues = new double[timestamps.length];
         this.sourcesNames = Arrays.asList(dataProcessor.getSourceNames());
         String[] tokensString = rpnExpression.split(" *, *");
@@ -767,7 +767,7 @@ class RpnCalculator {
 
     private static final class RpnStack {
         private static final int MAX_STACK_SIZE = 1000;
-        private double[] stack = new double[MAX_STACK_SIZE];
+        private final double[] stack = new double[MAX_STACK_SIZE];
         private int pos = 0;
 
         void push(double x) {

apps/jrobin/java/src/org/rrd4j/data/Source.java

@@ -34,7 +34,7 @@ abstract class Source {
      * @param tStart
      * @param tEnd
      * @return
-     * @deprecated This method is deprecated. Uses instance of {@link org.rrd4j.data.Variable}, used with DataProcessor.addDatasource(String, String, Variable)
+     * @deprecated This method is deprecated. Uses instance of {@link org.rrd4j.data.Variable}, used with {@link org.rrd4j.data.DataProcessor#addDatasource(String, String, Variable)}
      */
     @Deprecated
     Aggregates getAggregates(long tStart, long tEnd) {
@@ -47,7 +47,7 @@ abstract class Source {
      * @param tEnd
      * @param percentile
      * @return
-     * @deprecated This method is deprecated. Uses instance of {@link org.rrd4j.data.Variable.PERCENTILE}, used with DataProcessor.addDatasource(String, String, Variable)
+     * @deprecated This method is deprecated. Uses instance of {@link org.rrd4j.data.Variable.PERCENTILE}, used with {@link org.rrd4j.data.DataProcessor#addDatasource(String, String, Variable)}
      */
     @Deprecated
     double getPercentile(long tStart, long tEnd, double percentile) {

apps/jrobin/java/src/org/rrd4j/data/Variable.java

@@ -9,7 +9,7 @@ import org.rrd4j.core.Util;
 
 /**
  *  An abstract class to help extract single value from a set of value (VDEF in rrdtool)
- *  
+ * <p>
  *  It can be used to add new fancy statistical calculation with rrd values 
  *
  */
@@ -30,7 +30,7 @@ public abstract class Variable {
         public String toString() {
             return "Value [value=" + value + ", timestamp=" + timestamp + "]";
         }
-    };
+    }
 
     public static final Value INVALIDVALUE = new Value(0, Double.NaN);
 
@@ -101,7 +101,7 @@ public abstract class Variable {
 
     /**
      * This method is call with the needed values, extracted from the datasource to do the calculation.
-     * 
+     * <p>
      * Value is to be filled with both the double value and a possible timestamp, when it's used to find
      * a specific point
      * 
@@ -111,7 +111,7 @@ public abstract class Variable {
      * @param end the end of the period
      * @return a filled Value object
      */
-    protected abstract Value fill(long timestamps[], double[] values, long start, long end);
+    protected abstract Value fill(long[] timestamps, double[] values, long start, long end);
 
     /**
      * Find the first valid data point and it's timestamp
@@ -266,8 +266,8 @@ public abstract class Variable {
      *
      */
     static final class PercentElem {
-        long timestamp;
-        double value;
+        final long timestamp;
+        final double value;
 
         PercentElem(int pos, long timestamp, double value) {
             this.timestamp = timestamp;
@@ -305,7 +305,7 @@ public abstract class Variable {
      */
     static final class ComparPercentElemen implements Comparator<PercentElem>, Serializable {
         @Override
-        public final int compare(PercentElem arg0, PercentElem arg1) {
+        public int compare(PercentElem arg0, PercentElem arg1) {
             if (Double.isNaN(arg0.value) && Double.isNaN(arg1.value))
                 return Long.signum(arg0.timestamp - arg1.timestamp);
             else if (Double.isNaN(arg0.value))
@@ -346,7 +346,7 @@ public abstract class Variable {
         @Override
         protected Value fill(long[] timestamps, double[] values, long start, long end) {
             // valuesSet will be a set with NaN packet at the start
-            SortedSet<PercentElem> valuesSet = new TreeSet<PercentElem>(new ComparPercentElemen());
+            SortedSet<PercentElem> valuesSet = new TreeSet<>(new ComparPercentElemen());
             for (int i = 0 ; i < values.length ; i++) {
                 valuesSet.add(new PercentElem(i, timestamps[i], values[i]));
             }
@@ -356,7 +356,7 @@ public abstract class Variable {
                 valuesSet = valuesSet.tailSet(new PercentElem(0, 0, Double.NEGATIVE_INFINITY ));
             }
 
-            PercentElem[] element = (PercentElem[]) valuesSet.toArray(new PercentElem[valuesSet.size()]);
+            PercentElem[] element = valuesSet.toArray(new PercentElem[0]);
             int pos = Math.round(percentile * (element.length - 1) / 100);
             // if we have anything left...
             if (pos >= 0) {
@@ -395,15 +395,13 @@ public abstract class Variable {
             double SUMxx = 0.0;
             double lslslope;
 
-            for (int i = 0; i < values.length; i++) {
-                double value = values[i];
-
+            for (double value : values) {
                 if (!Double.isNaN(value)) {
                     cnt++;
 
                     SUMx += lslstep;
                     SUMxx += lslstep * lslstep;
-                    SUMy  += value;
+                    SUMy += value;
                     SUMxy += lslstep * value;
 
                 }
@@ -438,15 +436,13 @@ public abstract class Variable {
             double lslslope;
             double lslint;
 
-            for (int i = 0; i < values.length; i++) {
-                double value = values[i];
-
+            for (double value : values) {
                 if (!Double.isNaN(value)) {
                     cnt++;
 
                     SUMx += lslstep;
                     SUMxx += lslstep * lslstep;
-                    SUMy  += value;
+                    SUMy += value;
                     SUMxy += lslstep * value;
                 }
                 lslstep++;
@@ -481,15 +477,13 @@ public abstract class Variable {
             double SUMyy = 0.0;
             double lslcorrel;
 
-            for (int i = 0; i < values.length; i++) {
-                double value = values[i];
-
+            for (double value : values) {
                 if (!Double.isNaN(value)) {
                     cnt++;
 
                     SUMx += lslstep;
                     SUMxx += lslstep * lslstep;
-                    SUMy  += value;
+                    SUMy += value;
                     SUMxy += lslstep * value;
                     SUMyy += value * value;
                 }

apps/jrobin/java/src/org/rrd4j/graph/ConstantArea.java

@@ -13,6 +13,7 @@ public class ConstantArea extends Area {
         this.value = value;
     }
 
+    @Override
     void assignValues(DataProcessor dproc) {
         values = new double[dproc.getTimestamps().length];
         Arrays.fill(values, value);

apps/jrobin/java/src/org/rrd4j/graph/ConstantLine.java

@@ -14,6 +14,7 @@ public class ConstantLine extends Line {
         this.value = value;
     }
 
+    @Override
     void assignValues(DataProcessor dproc) {
         values = new double[dproc.getTimestamps().length];
         Arrays.fill(values, value);

apps/jrobin/java/src/org/rrd4j/graph/DownSampler.java

@@ -11,7 +11,7 @@ import java.util.Arrays;
  */
 public interface DownSampler {
 
-    public class DataSet {
+    class DataSet {
         public final long[] timestamps;
         public final double[] values;
         public DataSet(long[] timestamps, double[] values) {
@@ -25,6 +25,6 @@ public interface DownSampler {
 
     }
 
-    public DataSet downsize(long[] timestamps, double[] values);
+    DataSet downsize(long[] timestamps, double[] values);
 
 }

apps/jrobin/java/src/org/rrd4j/graph/ElementsNames.java

@@ -50,5 +50,5 @@ public enum ElementsNames {
     /**
      * The y-axis color
      */
-    yaxis;
+    yaxis
 }

apps/jrobin/java/src/org/rrd4j/graph/ImageWorker.java

@@ -8,12 +8,8 @@ import java.awt.Stroke;
 import java.awt.font.LineMetrics;
 import java.awt.geom.AffineTransform;
 import java.awt.image.BufferedImage;
-import java.io.BufferedInputStream;
-import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
-import java.io.FileInputStream;
 import java.io.IOException;
-import java.io.InputStream;
 import java.nio.file.Paths;
 
 import javax.imageio.IIOImage;
@@ -182,7 +178,7 @@ class ImageWorker {
 
         // Some format can't manage 16M colors images
         // JPEG don't like transparency
-        if (! imgProvider.canEncodeImage(outputImage) || "image/jpeg".equals(imgProvider.getMIMETypes()[0].toLowerCase())) {
+        if (! imgProvider.canEncodeImage(outputImage) || "image/jpeg".equalsIgnoreCase(imgProvider.getMIMETypes()[0])) {
             int w = img.getWidth();
             int h = img.getHeight();
             outputImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
@@ -208,15 +204,14 @@ class ImageWorker {
         }
     }
 
-    InputStream saveImage(String path, ImageWriter writer, ImageWriteParam iwp) throws IOException {
+    void saveImage(String path, ImageWriter writer, ImageWriteParam iwp) throws IOException {
         makeImage(Paths.get(path).toFile(), writer, iwp);
-        return new BufferedInputStream(new FileInputStream(path));
     }
 
-    InputStream getImageBytes(ImageWriter writer, ImageWriteParam iwp) throws IOException {
+    byte[] getImageBytes(ImageWriter writer, ImageWriteParam iwp) throws IOException {
         try (ByteArrayOutputStream stream = new ByteArrayOutputStream(IMG_BUFFER_CAPACITY)){
             makeImage(stream, writer, iwp);
-            return new ByteArrayInputStream(stream.toByteArray());
+            return stream.toByteArray();
         }
     }
 

apps/jrobin/java/src/org/rrd4j/graph/LegendComposer.java

@@ -6,13 +6,14 @@ import java.util.List;
 class LegendComposer implements RrdGraphConstants {
     private final RrdGraphDef gdef;
     private final ImageWorker worker;
-    private int legX, legY;
+    private final int legX;
+    private int legY;
     private final int legWidth;
 
-    private double interLegendSpace;
-    private double leading;
-    private double smallLeading;
-    private double boxSpace;
+    private final double interLegendSpace;
+    private final double leading;
+    private final double smallLeading;
+    private final double boxSpace;
 
     LegendComposer(RrdGraph rrdGraph, int legX, int legY, int legWidth) {
         this.gdef = rrdGraph.gdef;
@@ -46,7 +47,7 @@ class LegendComposer implements RrdGraphConstants {
         private double width;
         private int spaceCount;
         private boolean noJustification;
-        private List<CommentText> comments = new ArrayList<CommentText>();
+        private final List<CommentText> comments = new ArrayList<>();
 
         Line() {
             clear();

apps/jrobin/java/src/org/rrd4j/graph/Mapper.java

@@ -10,10 +10,10 @@ class Mapper {
         this.im = rrdGraph.im;
         pixieX = (double) im.xsize / (double) (im.end - im.start);
         if (!gdef.logarithmic) {
-            pixieY = (double) im.ysize / (im.maxval - im.minval);
+            pixieY = im.ysize / (im.maxval - im.minval);
         }
         else {
-            pixieY = (double) im.ysize / (ValueAxisLogarithmic.log10(im.maxval) - ValueAxisLogarithmic.log10(im.minval));
+            pixieY = im.ysize / (ValueAxisLogarithmic.log10(im.maxval) - ValueAxisLogarithmic.log10(im.minval));
         }
     }
 
@@ -22,15 +22,15 @@ class Mapper {
         this.im = im;
         pixieX = (double) im.xsize / (double) (im.end - im.start);
         if (!gdef.logarithmic) {
-            pixieY = (double) im.ysize / (im.maxval - im.minval);
+            pixieY = im.ysize / (im.maxval - im.minval);
         }
         else {
-            pixieY = (double) im.ysize / (Math.log10(im.maxval) - Math.log10(im.minval));
+            pixieY = im.ysize / (Math.log10(im.maxval) - Math.log10(im.minval));
         }
     }
 
     int xtr(double mytime) {
-        return (int) ((double) im.xorigin + pixieX * (mytime - im.start));
+        return (int) (im.xorigin + pixieX * (mytime - im.start));
     }
 
     int ytr(double value) {

apps/jrobin/java/src/org/rrd4j/graph/PDef.java

@@ -4,7 +4,7 @@ import org.rrd4j.data.DataProcessor;
 import org.rrd4j.data.IPlottable;
 
 class PDef extends Source {
-    private IPlottable plottable;
+    private final IPlottable plottable;
 
     PDef(String name, IPlottable plottable) {
         super(name);

apps/jrobin/java/src/org/rrd4j/graph/PathIterator.java

@@ -1,7 +1,7 @@
 package org.rrd4j.graph;
 
 class PathIterator {
-    private double[] y;
+    private final double[] y;
     private int pos = 0;
 
     PathIterator(double[] y) {

apps/jrobin/java/src/org/rrd4j/graph/PrintText.java

@@ -26,10 +26,12 @@ class PrintText extends CommentText {
         this.strftime = strftime;
     }
 
+    @Override
     boolean isPrint() {
         return !includedInGraph;
     }
 
+    @Override
     void resolveText(Locale l, DataProcessor dproc, ValueScaler valueScaler) {
         super.resolveText(l, dproc, valueScaler);
         Value v = dproc.getVariable(srcName);

apps/jrobin/java/src/org/rrd4j/graph/RrdGraph.java

@@ -7,6 +7,10 @@ import java.awt.Graphics;
 import java.awt.Paint;
 import java.awt.Stroke;
 import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
 
 import javax.imageio.ImageIO;
 import javax.imageio.ImageWriteParam;
@@ -172,10 +176,27 @@ public class RrdGraph implements RrdGraphConstants {
 
     private void saveImage() throws IOException {
         if (! RrdGraphConstants.IN_MEMORY_IMAGE.equals(gdef.filename)) {
-            info.stream = worker.saveImage(gdef.filename, writer, param);
+            Path imgpath = Paths.get(gdef.filename);
+            worker.saveImage(gdef.filename, writer, param);
+            info.bytesSource = () -> {
+                try {
+                    return Files.readAllBytes(imgpath);
+                } catch (IOException e) {
+                    throw new IllegalStateException("Unable to read image bytes", e);
+                }
+            };
+            info.bytesCount = () -> {
+                try {
+                    return (int) Files.size(imgpath);
+                } catch (IOException e) {
+                    throw new IllegalStateException("Unable to read image informations", e);
+               }
+            };
         }
         else {
-            info.stream = worker.getImageBytes(writer, param);
+            byte[] content = worker.getImageBytes(writer, param);
+            info.bytesSource = () -> Arrays.copyOf(content, content.length);
+            info.bytesCount = () -> content.length;
         }
     }
 
@@ -248,10 +269,9 @@ public class RrdGraph implements RrdGraphConstants {
                 worker.drawString(gdef.title, x, y, gdef.getFont(FONTTAG_TITLE), gdef.getColor(ElementsNames.font));
             }
             if (gdef.verticalLabel != null) {
-                int x = PADDING_LEFT;
                 int y = im.yorigin - im.ysize / 2 + (int) worker.getStringWidth(gdef.verticalLabel, gdef.getFont(FONTTAG_UNIT)) / 2;
                 int ascent = (int) worker.getFontAscent(gdef.getFont(FONTTAG_UNIT));
-                worker.transform(x, y, -Math.PI / 2);
+                worker.transform(PADDING_LEFT, y, -Math.PI / 2);
                 worker.drawString(gdef.verticalLabel, 0, ascent, gdef.getFont(FONTTAG_UNIT), gdef.getColor(ElementsNames.font));
                 worker.reset();
             }
@@ -375,8 +395,7 @@ public class RrdGraph implements RrdGraphConstants {
                     im.xorigin + im.xsize + 4,
             };
             double[] Xarrow_y = {
-                    im.yorigin - 3,
-                    im.yorigin + 0,
+                    im.yorigin - 3, im.yorigin,
                     im.yorigin + 3,
             };
             worker.fillPolygon(Xarrow_x, im.yorigin + 3.0, Xarrow_y, arrowColor);
@@ -428,7 +447,7 @@ public class RrdGraph implements RrdGraphConstants {
             im.xorigin = 0;
         }
         else {
-            im.xorigin = (int) (PADDING_LEFT + im.unitslength * getFontCharWidth(FontTag.UNIT));
+            im.xorigin = (int) (PADDING_LEFT + im.unitslength * getFontCharWidth(FONTTAG_AXIS));
         }
 
         if (!gdef.onlyGraph && gdef.verticalLabel != null) {
@@ -452,7 +471,7 @@ public class RrdGraph implements RrdGraphConstants {
         }
         else {
             im.xgif = PADDING_RIGHT + im.xsize + im.xorigin;
-            im.ygif = im.yorigin + (int) (PADDING_PLOT * getFontHeight(FONTTAG_DEFAULT));
+            im.ygif = im.yorigin + (int) (PADDING_PLOT * getFontHeight(FONTTAG_AXIS));
         }
     }
 
@@ -566,10 +585,10 @@ public class RrdGraph implements RrdGraphConstants {
                 }
             }
             else {
-                im.minval = (double) im.ylabfact * im.ygridstep *
-                        Math.floor(im.minval / ((double) im.ylabfact * im.ygridstep));
-                im.maxval = (double) im.ylabfact * im.ygridstep *
-                        Math.ceil(im.maxval / ((double) im.ylabfact * im.ygridstep));
+                im.minval = im.ylabfact * im.ygridstep *
+                        Math.floor(im.minval / (im.ylabfact * im.ygridstep));
+                im.maxval = im.ylabfact * im.ygridstep *
+                        Math.ceil(im.maxval / (im.ylabfact * im.ygridstep));
             }
 
         }
@@ -658,7 +677,7 @@ public class RrdGraph implements RrdGraphConstants {
 
     private void fetchData() throws IOException {
         dproc = new DataProcessor(gdef.startTime, gdef.endTime);
-        dproc.setPixelCount(im.xsize);
+        dproc.setPixelCount(gdef.width);
         if (gdef.poolUsed) {
             dproc.setPoolUsed(gdef.poolUsed);
             dproc.setPool(gdef.getPool());

apps/jrobin/java/src/org/rrd4j/graph/RrdGraphConstants.java

@@ -293,32 +293,32 @@ public interface RrdGraphConstants {
     /**
      * The file that contains font configuration searched in the class path. The default value is <code>/rrd4jfonts.properties</code>
      */
-    public static final String PROPERTYFONTSPROPERTIES = "org.rrd4j.fonts.properties";
+    String PROPERTYFONTSPROPERTIES = "org.rrd4j.fonts.properties";
     /**
      * A possible URL to a configuration file.
      */
-    public static final String PROPERTYFONTSURL = "org.rrd4j.fonts.properties.url";
+    String PROPERTYFONTSURL = "org.rrd4j.fonts.properties.url";
     /**
-     * The name of the plain font, used to define the {@link #DEFAULT_SMALL_FONT} and the {@link GATOR_FONT}. To be found in the classpath.
+     * The name of the plain font, used to define the {@link #DEFAULT_SMALL_FONT} and the {@link RrdGraphDef#GATOR_FONT}. To be found in the classpath.
      */
-    public static final String PROPERTYFONTPLAIN = "org.rrd4j.font.plain";
+    String PROPERTYFONTPLAIN = "org.rrd4j.font.plain";
     /**
      * The name of the bold font, used to define the {@link #DEFAULT_LARGE_FONT}. To be found in the classpath.
      */
-    public static final String PROPERTYFONTBOLD = "org.rrd4j.font.bold";
+    String PROPERTYFONTBOLD = "org.rrd4j.font.bold";
     /**
-     * An URL to the plain font, used to define the {@link #DEFAULT_SMALL_FONT} and the {@link GATOR_FONT}.
+     * An URL to the plain font, used to define the {@link #DEFAULT_SMALL_FONT} and the {@link RrdGraphDef#GATOR_FONT}.
      */
-    public static final String PROPERTYFONTPLAINURL = "org.rrd4j.font.plain.url";
+    String PROPERTYFONTPLAINURL = "org.rrd4j.font.plain.url";
     /**
      * An URL to the bold font, used to define the {@link #DEFAULT_LARGE_FONT}.
      */
-    public static final String PROPERTYFONTBOLDURL = "org.rrd4j.font.bold.url";
+    String PROPERTYFONTBOLDURL = "org.rrd4j.font.bold.url";
 
     /**
      * Font constructor, to use embedded fonts. Not really useful outside internal use for RRD4J.
      */
-    static class FontConstructor {
+    class FontConstructor {
         private static final Properties fileProps = new Properties();
         static {
             refreshConf();
@@ -364,7 +364,7 @@ public interface RrdGraphConstants {
          */
         public static Font getFont(int type, int size) {
 /*
-            Function<String, InputStream> fontStream = null;
+            Function<String, InputStream> fontStream;
             String fontPath = fileProps.getProperty(type == Font.BOLD ? PROPERTYFONTBOLDURL : PROPERTYFONTPLAINURL);
             if (fontPath!= null) {
                 fontStream = s -> {
@@ -391,15 +391,15 @@ public interface RrdGraphConstants {
     /**
      * Default graph small font
      */
-    static final Font DEFAULT_SMALL_FONT = FontConstructor.getFont(Font.PLAIN, 10);
+    Font DEFAULT_SMALL_FONT = FontConstructor.getFont(Font.PLAIN, 10);
     /**
      * Default graph large font
      */
-    static final Font DEFAULT_LARGE_FONT = FontConstructor.getFont(Font.BOLD, 12);
+    Font DEFAULT_LARGE_FONT = FontConstructor.getFont(Font.BOLD, 12);
     /**
      * Font for the Gator
      */
-    static final Font GATOR_FONT = FontConstructor.getFont(Font.PLAIN, 9);
+    Font GATOR_FONT = FontConstructor.getFont(Font.PLAIN, 9);
     /**
      * Used internally
      */
@@ -466,7 +466,7 @@ public interface RrdGraphConstants {
     /**
      * Allowed font tag names which can be used in {@link org.rrd4j.graph.RrdGraphDef#setFont(org.rrd4j.graph.RrdGraphConstants.FontTag, java.awt.Font)} method
      */
-    public enum FontTag  {
+    enum FontTag  {
         /**
          * Index of the default font. Used in {@link org.rrd4j.graph.RrdGraphDef#setFont(org.rrd4j.graph.RrdGraphConstants.FontTag, java.awt.Font)}
          */
@@ -508,7 +508,7 @@ public interface RrdGraphConstants {
 
     FontTag FONTTAG_AXIS      = FontTag.AXIS;
 
-    FontTag FONTTAG_UNIT      = FontTag.AXIS;
+    FontTag FONTTAG_UNIT      = FontTag.UNIT;
 
     FontTag FONTTAG_LEGEND    = FontTag.LEGEND;
 

apps/jrobin/java/src/org/rrd4j/graph/RrdGraphDef.java

@@ -172,9 +172,9 @@ public class RrdGraphDef implements RrdGraphConstants, DataHolder {
     Stroke tickStroke = TICK_STROKE;
     DownSampler downsampler = null;
 
-    final List<Source> sources = new ArrayList<Source>();
-    final List<CommentText> comments = new ArrayList<CommentText>();
-    final List<PlotElement> plotElements = new ArrayList<PlotElement>();
+    final List<Source> sources = new ArrayList<>();
+    final List<CommentText> comments = new ArrayList<>();
+    final List<PlotElement> plotElements = new ArrayList<>();
 
     /**
      * Creates RrdGraphDef object and sets default time span (default ending time is 'now',
@@ -580,9 +580,9 @@ public class RrdGraphDef implements RrdGraphConstants, DataHolder {
 
     /**
      * Sets image format.
-     * ImageIO is used to save the image, so any supported format by ImageIO can be used, and it can be extended using https://github.com/geosolutions-it/imageio-ext.
+     * ImageIO is used to save the image, so any supported format by ImageIO can be used, and it can be extended using <a href="https://github.com/geosolutions-it/imageio-ext">...</a>.
      *
-     * @param imageFormat Any value as return by {@link javax.imageio.ImageIO#getReaderFormatNames}
+     * @param imageFormat Any value as return by {@link ImageIO#getReaderFormatNames}
      */
     public void setImageFormat(String imageFormat) {
         this.imageFormat = imageFormat;
@@ -590,7 +590,7 @@ public class RrdGraphDef implements RrdGraphConstants, DataHolder {
 
     /**
      * Sets background image.
-     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using https://github.com/geosolutions-it/imageio-ext.
+     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using <a href="https://github.com/geosolutions-it/imageio-ext">...</a>.
      *
      * @param backgroundImage Path to background image
      */
@@ -600,7 +600,7 @@ public class RrdGraphDef implements RrdGraphConstants, DataHolder {
 
     /**
      * Sets background image.
-     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using https://github.com/geosolutions-it/imageio-ext.
+     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using <a href="https://github.com/geosolutions-it/imageio-ext">...</a>.
      *
      * @param backgroundImageUrl URL to background image
      */
@@ -619,7 +619,7 @@ public class RrdGraphDef implements RrdGraphConstants, DataHolder {
 
     /**
      * Sets canvas background image. Canvas image is printed on canvas area, under canvas color and plot.
-     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using https://github.com/geosolutions-it/imageio-ext.
+     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using <a href="https://github.com/geosolutions-it/imageio-ext">...</a>.
      *
      * @param canvasImage Path to canvas image
      */
@@ -629,7 +629,7 @@ public class RrdGraphDef implements RrdGraphConstants, DataHolder {
 
     /**
      * Sets canvas background image. Canvas image is printed on canvas area, under canvas color and plot.
-     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using https://github.com/geosolutions-it/imageio-ext.
+     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using <a href="https://github.com/geosolutions-it/imageio-ext">...</a>.
      *
      * @param canvasUrl URL to canvas image
      */
@@ -648,7 +648,7 @@ public class RrdGraphDef implements RrdGraphConstants, DataHolder {
 
     /**
      * Sets overlay image. Overlay image is printed on the top of the image, once it is completely created.
-     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using https://github.com/geosolutions-it/imageio-ext.
+     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using <a href="https://github.com/geosolutions-it/imageio-ext">...</a>.
      *
      * @param overlayImage Path to overlay image
      */
@@ -658,7 +658,7 @@ public class RrdGraphDef implements RrdGraphConstants, DataHolder {
 
     /**
      * Sets overlay image. Overlay image is printed on the top of the image, once it is completely created.
-     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using https://github.com/geosolutions-it/imageio-ext.
+     * ImageIO is used to download, so any supported format by ImageIO can be used, and it can be extended using <a href="https://github.com/geosolutions-it/imageio-ext">...</a>.
      *
      * @param overlayImage URL to overlay image
      */
@@ -1118,7 +1118,7 @@ public class RrdGraphDef implements RrdGraphConstants, DataHolder {
     /**
      * Creates a datasource that performs a variable calculation on an
      * another named datasource to yield a single combined timestamp/value.
-     *
+     * <p>
      * Requires that the other datasource has already been defined; otherwise, it'll
      * end up with no data
      *

apps/jrobin/java/src/org/rrd4j/graph/RrdGraphInfo.java

@@ -1,9 +1,8 @@
 package org.rrd4j.graph;
 
-import java.io.IOException;
-import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Supplier;
 
 /**
  * Class to represent successfully created Rrd4j graph. Objects of this class are created by method
@@ -12,9 +11,10 @@ import java.util.List;
 public class RrdGraphInfo {
     String filename;
     int width, height;
-    InputStream stream;
+    Supplier<byte[]> bytesSource;
+    Supplier<Integer> bytesCount;
     String imgInfo;
-    private List<String> printLines = new ArrayList<String>();
+    private final List<String> printLines = new ArrayList<>();
 
     RrdGraphInfo() {
         // cannot instantiate this class
@@ -58,16 +58,7 @@ public class RrdGraphInfo {
      * @throws IllegalStateException if the images bytes are unavailable or can't be read
      */
     public byte[] getBytes() {
-        try {
-            byte[] content = new byte[stream.available()];
-            int read = stream.read(content);
-            if (read != content.length) {
-                throw new IllegalStateException("Unable to read image buffer");
-            }
-            return content;
-        } catch (IOException e) {
-            throw new IllegalStateException("Unable to read image bytes", e);
-        }
+        return bytesSource.get();
     }
 
     /**
@@ -76,7 +67,7 @@ public class RrdGraphInfo {
      * @return An array of formatted PRINT lines
      */
     public String[] getPrintLines() {
-        return printLines.toArray(new String[printLines.size()]);
+        return printLines.toArray(new String[0]);
     }
 
     /**
@@ -95,11 +86,7 @@ public class RrdGraphInfo {
      * @throws IllegalStateException if the images bytes are unavailable
      */
     public int getByteCount() {
-        try {
-            return stream.available();
-        } catch (IOException e) {
-            throw new IllegalStateException("Unable to read image bytes", e);
-        }
+        return bytesCount.get();
     }
 
     /**

apps/jrobin/java/src/org/rrd4j/graph/Stack.java

@@ -10,6 +10,7 @@ class Stack extends SourcedPlotElement {
         super(srcName, color, parent);
     }
 
+    @Override
     void assignValues(DataProcessor dproc) {
         double[] parentValues = parent.getValues();
         double[] procValues = dproc.getValues(srcName);
@@ -40,6 +41,7 @@ class Stack extends SourcedPlotElement {
         }
     }
 
+    @Override
     Paint getParentColor() {
         return parent.color;
     }

apps/jrobin/java/src/org/rrd4j/graph/ValueAxis.java

@@ -2,6 +2,8 @@ package org.rrd4j.graph;
 
 import java.awt.Font;
 import java.awt.Paint;
+import java.math.BigDecimal;
+import java.math.MathContext;
 
 import org.rrd4j.core.Util;
 
@@ -106,6 +108,10 @@ class ValueAxis extends Axis {
                 }
                 gridstep = selectedYLabel.grid * im.magfact;
                 labfact = findLabelFactor(selectedYLabel);
+                if(labfact == -1) {
+                    // as a fallback, use the largest label factor of the selected label
+                    labfact = selectedYLabel.labelFacts[3];
+                }
             }
         }
         else {
@@ -116,13 +122,14 @@ class ValueAxis extends Axis {
         int sgrid = (int) (im.minval / gridstep - 1);
         int egrid = (int) (im.maxval / gridstep + 1);
         double scaledstep = gridstep / im.magfact;
+        boolean fractional = isFractional(scaledstep, labfact);
         for (int i = sgrid; i <= egrid; i++) {
             int y = mapper.ytr(gridstep * i);
             if (y >= im.yorigin - im.ysize && y <= im.yorigin) {
                 if (i % labfact == 0) {
                     String graph_label;
                     if (i == 0 || im.symbol == ' ') {
-                        if (scaledstep < 1) {
+                        if (fractional) {
                             if (i != 0 && gdef.altYGrid) {
                                 graph_label = Util.sprintf(gdef.locale, labfmt, scaledstep * i);
                             }
@@ -135,7 +142,7 @@ class ValueAxis extends Axis {
                         }
                     }
                     else {
-                        if (scaledstep < 1) {
+                        if (fractional) {
                             graph_label = Util.sprintf(gdef.locale, "%4.1f %c", scaledstep * i, im.symbol);
                         }
                         else {
@@ -163,7 +170,7 @@ class ValueAxis extends Axis {
      * If the graph covers positive and negative on the y-axis, then
      * desiredMinimumLabelCount is checked as well, to ensure the chosen YLabel definition
      * will result in the required number of labels
-     * 
+     * <p>
      * Returns null if none are acceptable (none the right size or with
      * enough labels)
      */
@@ -237,6 +244,18 @@ class ValueAxis extends Axis {
         return range / im.magfact;
     }
 
+    /**
+     * Returns true if some or all labels have fractional part (other than zero).
+     */
+    private static boolean isFractional(double scaledstep, int labfact) {
+        if (scaledstep >= 1) {
+            return false;
+        }
+        BigDecimal bd = BigDecimal.valueOf(scaledstep)
+                .multiply(BigDecimal.valueOf(labfact), MathContext.DECIMAL32);
+        return !(bd.signum() == 0 || bd.scale() <= 0 || bd.stripTrailingZeros().scale() <= 0);
+    }
+
     static class YLabel {
         final double grid;
         final int[] labelFacts;

apps/jrobin/java/src/org/rrd4j/graph/ValueAxisLogarithmic.java

@@ -43,7 +43,7 @@ class ValueAxisLogarithmic extends Axis {
         if (im.maxval == im.minval) {
             return false;
         }
-        double pixpex = (double) im.ysize / (log10(im.maxval) - log10(im.minval));
+        double pixpex = im.ysize / (log10(im.maxval) - log10(im.minval));
         if (Double.isNaN(pixpex)) {
             return false;
         }

apps/jrobin/java/src/org/rrd4j/graph/ValueScaler.java

@@ -2,7 +2,7 @@ package org.rrd4j.graph;
 
 class ValueScaler {
     static final String UNIT_UNKNOWN = "?";
-    static final String UNIT_SYMBOLS[] = {
+    static final String[] UNIT_SYMBOLS = {
             "a", "f", "p", "n", "u", "m", " ", "k", "M", "G", "T", "P", "E"
     };
     static final int SYMB_CENTER = 6;
@@ -55,8 +55,8 @@ class ValueScaler {
     }
 
     static class Scaled {
-        double value;
-        String unit;
+        final double value;
+        final String unit;
 
         public Scaled(double value, String unit) {
             this.value = value;