Checkstyle: private final class should be declared as final

commons-rng-core/src/main/java/org/apache/commons/rng/core/source32/JDKRandom.java

@@ -57,7 +57,7 @@ public class JDKRandom extends IntProvider {
      * @see <a href="http://www.ibm.com/developerworks/library/se-lookahead/">
      *  IBM DeveloperWorks Article: Look-ahead Java deserialization</a>
      */
-    private static class ValidatingObjectInputStream extends ObjectInputStream {
+    private static final class ValidatingObjectInputStream extends ObjectInputStream {
         /**
          * @param in Input stream
          * @throws IOException Signals that an I/O exception has occurred.

commons-rng-core/src/test/java/org/apache/commons/rng/core/SplittableProvidersParametricTest.java

@@ -45,7 +45,7 @@ class SplittableProvidersParametricTest {
      * All generation and split methods throw an exception. This can be used to test
      * exception conditions for arguments to default stream functions.
      */
-    private static class DummyGenerator implements SplittableUniformRandomProvider {
+    private static final class DummyGenerator implements SplittableUniformRandomProvider {
         /** An instance. */
         static final DummyGenerator INSTANCE = new DummyGenerator();
 
@@ -65,7 +65,7 @@ public SplittableUniformRandomProvider split(UniformRandomProvider source) {
      * Generation methods default to ThreadLocalRandom. Split methods return the same instance.
      * This is a functioning generator that can be used as a source to seed splitting.
      */
-    private static class ThreadLocalGenerator implements SplittableUniformRandomProvider {
+    private static final class ThreadLocalGenerator implements SplittableUniformRandomProvider {
         /** An instance. */
         static final ThreadLocalGenerator INSTANCE = new ThreadLocalGenerator();
 

commons-rng-core/src/test/java/org/apache/commons/rng/core/source32/L32X64MixTest.java

@@ -35,7 +35,7 @@ class L32X64MixTest extends AbstractLXMTest {
      * Factory to create a composite LXM generator that is equivalent
      * to the RNG under test.
      */
-    private static class Factory implements LXMGeneratorFactory {
+    private static final class Factory implements LXMGeneratorFactory {
         static final Factory INSTANCE = new Factory();
 
         @Override

commons-rng-core/src/test/java/org/apache/commons/rng/core/source64/L128X1024MixTest.java

@@ -34,7 +34,7 @@ class L128X1024MixTest extends AbstractLXMTest {
      * Factory to create a composite LXM generator that is equivalent
      * to the RNG under test.
      */
-    private static class Factory implements LXMGeneratorFactory {
+    private static final class Factory implements LXMGeneratorFactory {
         static final Factory INSTANCE = new Factory();
 
         @Override

commons-rng-core/src/test/java/org/apache/commons/rng/core/source64/L128X128MixTest.java

@@ -35,7 +35,7 @@ class L128X128MixTest extends AbstractLXMTest {
      * Factory to create a composite LXM generator that is equivalent
      * to the RNG under test.
      */
-    private static class Factory implements LXMGeneratorFactory {
+    private static final class Factory implements LXMGeneratorFactory {
         static final Factory INSTANCE = new Factory();
 
         @Override

commons-rng-core/src/test/java/org/apache/commons/rng/core/source64/L128X256MixTest.java

@@ -35,7 +35,7 @@ class L128X256MixTest extends AbstractLXMTest {
      * Factory to create a composite LXM generator that is equivalent
      * to the RNG under test.
      */
-    private static class Factory implements LXMGeneratorFactory {
+    private static final class Factory implements LXMGeneratorFactory {
         static final Factory INSTANCE = new Factory();
 
         @Override

commons-rng-core/src/test/java/org/apache/commons/rng/core/source64/L64X1024MixTest.java

@@ -34,7 +34,7 @@ class L64X1024MixTest extends AbstractLXMTest {
      * Factory to create a composite LXM generator that is equivalent
      * to the RNG under test.
      */
-    private static class Factory implements LXMGeneratorFactory {
+    private static final class Factory implements LXMGeneratorFactory {
         static final Factory INSTANCE = new Factory();
 
         @Override

commons-rng-core/src/test/java/org/apache/commons/rng/core/source64/L64X128MixTest.java

@@ -35,7 +35,7 @@ class L64X128MixTest extends AbstractLXMTest {
      * Factory to create a composite LXM generator that is equivalent
      * to the RNG under test.
      */
-    private static class Factory implements LXMGeneratorFactory {
+    private static final class Factory implements LXMGeneratorFactory {
         static final Factory INSTANCE = new Factory();
 
         @Override

commons-rng-core/src/test/java/org/apache/commons/rng/core/source64/L64X128StarStarTest.java

@@ -35,7 +35,7 @@ class L64X128StarStarTest extends AbstractLXMTest {
      * Factory to create a composite LXM generator that is equivalent
      * to the RNG under test.
      */
-    private static class Factory implements LXMGeneratorFactory {
+    private static final class Factory implements LXMGeneratorFactory {
         static final Factory INSTANCE = new Factory();
 
         @Override

commons-rng-core/src/test/java/org/apache/commons/rng/core/source64/L64X256MixTest.java

@@ -35,7 +35,7 @@ class L64X256MixTest extends AbstractLXMTest {
      * Factory to create a composite LXM generator that is equivalent
      * to the RNG under test.
      */
-    private static class Factory implements LXMGeneratorFactory {
+    private static final class Factory implements LXMGeneratorFactory {
         static final Factory INSTANCE = new Factory();
 
         @Override

commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/CompositeSamplers.java

@@ -125,7 +125,7 @@ public SharedStateDiscreteSampler create(UniformRandomProvider rng, double[] pro
      * sampler given a factory and the probability distribution. Each new instance will recreate
      * the distribution sampler using the factory.
      */
-    private static class SharedStateDiscreteProbabilitySampler implements SharedStateDiscreteSampler {
+    private static final class SharedStateDiscreteProbabilitySampler implements SharedStateDiscreteSampler {
         /** The sampler. */
         private final DiscreteSampler sampler;
         /** The factory to create a new discrete sampler. */
@@ -243,7 +243,7 @@ public interface Builder<S> {
      *
      * @param <S> Type of sampler
      */
-    private static class SamplerBuilder<S> implements Builder<S> {
+    private static final class SamplerBuilder<S> implements Builder<S> {
         /** The specialisation of the sampler. */
         private final Specialisation specialisation;
         /** The weighted samplers. */
@@ -295,7 +295,7 @@ S createSampler(DiscreteSampler discreteSampler,
          *
          * @param <S> Sampler type
          */
-        private static class WeightedSampler<S> {
+        private static final class WeightedSampler<S> {
             /** The weight. */
             private final double weight;
             /** The sampler. */
@@ -593,7 +593,7 @@ S nextSampler() {
      *
      * @param <T> Type of sample
      */
-    private static class ObjectSamplerFactory<T> implements
+    private static final class ObjectSamplerFactory<T> implements
             SamplerBuilder.SamplerFactory<ObjectSampler<T>> {
         /** The instance. */
         @SuppressWarnings("rawtypes")
@@ -621,7 +621,7 @@ public ObjectSampler<T> createSampler(DiscreteSampler discreteSampler,
          *
          * @param <T> Type of sample
          */
-        private static class CompositeObjectSampler<T>
+        private static final class CompositeObjectSampler<T>
                 extends CompositeSampler<ObjectSampler<T>>
                 implements ObjectSampler<T> {
             /**
@@ -645,7 +645,7 @@ public T sample() {
      *
      * @param <T> Type of sample
      */
-    private static class SharedStateObjectSamplerFactory<T> implements
+    private static final class SharedStateObjectSamplerFactory<T> implements
             SamplerBuilder.SamplerFactory<SharedStateObjectSampler<T>> {
         /** The instance. */
         @SuppressWarnings("rawtypes")
@@ -678,7 +678,7 @@ public SharedStateObjectSampler<T> createSampler(DiscreteSampler discreteSampler
          *
          * @param <T> Type of sample
          */
-        private static class CompositeSharedStateObjectSampler<T>
+        private static final class CompositeSharedStateObjectSampler<T>
                 extends CompositeSampler<SharedStateObjectSampler<T>>
                 implements SharedStateObjectSampler<T> {
             /**
@@ -708,7 +708,7 @@ public CompositeSharedStateObjectSampler<T> withUniformRandomProvider(UniformRan
     /**
      * A factory for creating a composite DiscreteSampler.
      */
-    private static class DiscreteSamplerFactory implements
+    private static final class DiscreteSamplerFactory implements
             SamplerBuilder.SamplerFactory<DiscreteSampler> {
         /** The instance. */
         static final DiscreteSamplerFactory INSTANCE = new DiscreteSamplerFactory();
@@ -722,7 +722,7 @@ public DiscreteSampler createSampler(DiscreteSampler discreteSampler,
         /**
          * A composite discrete sampler.
          */
-        private static class CompositeDiscreteSampler
+        private static final class CompositeDiscreteSampler
                 extends CompositeSampler<DiscreteSampler>
                 implements DiscreteSampler {
             /**
@@ -744,7 +744,7 @@ public int sample() {
     /**
      * A factory for creating a composite SharedStateDiscreteSampler.
      */
-    private static class SharedStateDiscreteSamplerFactory implements
+    private static final class SharedStateDiscreteSamplerFactory implements
             SamplerBuilder.SamplerFactory<SharedStateDiscreteSampler> {
         /** The instance. */
         static final SharedStateDiscreteSamplerFactory INSTANCE = new SharedStateDiscreteSamplerFactory();
@@ -760,7 +760,7 @@ public SharedStateDiscreteSampler createSampler(DiscreteSampler discreteSampler,
         /**
          * A composite discrete sampler with shared state support.
          */
-        private static class CompositeSharedStateDiscreteSampler
+        private static final class CompositeSharedStateDiscreteSampler
                 extends CompositeSampler<SharedStateDiscreteSampler>
                 implements SharedStateDiscreteSampler {
             /**
@@ -790,7 +790,7 @@ public CompositeSharedStateDiscreteSampler withUniformRandomProvider(UniformRand
     /**
      * A factory for creating a composite ContinuousSampler.
      */
-    private static class ContinuousSamplerFactory implements
+    private static final class ContinuousSamplerFactory implements
             SamplerBuilder.SamplerFactory<ContinuousSampler> {
         /** The instance. */
         static final ContinuousSamplerFactory INSTANCE = new ContinuousSamplerFactory();
@@ -804,7 +804,7 @@ public ContinuousSampler createSampler(DiscreteSampler discreteSampler,
         /**
          * A composite continuous sampler.
          */
-        private static class CompositeContinuousSampler
+        private static final class CompositeContinuousSampler
                 extends CompositeSampler<ContinuousSampler>
                 implements ContinuousSampler {
             /**
@@ -826,7 +826,7 @@ public double sample() {
     /**
      * A factory for creating a composite SharedStateContinuousSampler.
      */
-    private static class SharedStateContinuousSamplerFactory implements
+    private static final class SharedStateContinuousSamplerFactory implements
             SamplerBuilder.SamplerFactory<SharedStateContinuousSampler> {
         /** The instance. */
         static final SharedStateContinuousSamplerFactory INSTANCE = new SharedStateContinuousSamplerFactory();
@@ -842,7 +842,7 @@ public SharedStateContinuousSampler createSampler(DiscreteSampler discreteSample
         /**
          * A composite continuous sampler with shared state support.
          */
-        private static class CompositeSharedStateContinuousSampler
+        private static final class CompositeSharedStateContinuousSampler
                 extends CompositeSampler<SharedStateContinuousSampler>
                 implements SharedStateContinuousSampler {
             /**
@@ -872,7 +872,7 @@ public CompositeSharedStateContinuousSampler withUniformRandomProvider(UniformRa
     /**
      * A factory for creating a composite LongSampler.
      */
-    private static class LongSamplerFactory implements
+    private static final class LongSamplerFactory implements
             SamplerBuilder.SamplerFactory<LongSampler> {
         /** The instance. */
         static final LongSamplerFactory INSTANCE = new LongSamplerFactory();
@@ -886,7 +886,7 @@ public LongSampler createSampler(DiscreteSampler discreteSampler,
         /**
          * A composite long sampler.
          */
-        private static class CompositeLongSampler
+        private static final class CompositeLongSampler
                 extends CompositeSampler<LongSampler>
                 implements LongSampler {
             /**
@@ -908,7 +908,7 @@ public long sample() {
     /**
      * A factory for creating a composite SharedStateLongSampler.
      */
-    private static class SharedStateLongSamplerFactory implements
+    private static final class SharedStateLongSamplerFactory implements
             SamplerBuilder.SamplerFactory<SharedStateLongSampler> {
         /** The instance. */
         static final SharedStateLongSamplerFactory INSTANCE = new SharedStateLongSamplerFactory();
@@ -924,7 +924,7 @@ public SharedStateLongSampler createSampler(DiscreteSampler discreteSampler,
         /**
          * A composite long sampler with shared state support.
          */
-        private static class CompositeSharedStateLongSampler
+        private static final class CompositeSharedStateLongSampler
                 extends CompositeSampler<SharedStateLongSampler>
                 implements SharedStateLongSampler {
             /**

commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/UnitSphereSampler.java

@@ -57,7 +57,7 @@ public class UnitSphereSampler implements SharedStateObjectSampler<double[]> {
     /**
      * Sample uniformly from the ends of a 1D unit line.
      */
-    private static class UnitSphereSampler1D extends UnitSphereSampler {
+    private static final class UnitSphereSampler1D extends UnitSphereSampler {
         /** The source of randomness. */
         private final UniformRandomProvider rng;
 
@@ -87,7 +87,7 @@ public UnitSphereSampler withUniformRandomProvider(UniformRandomProvider rng) {
      * Sample uniformly from a 2D unit circle.
      * This is a 2D specialisation of the UnitSphereSamplerND.
      */
-    private static class UnitSphereSampler2D extends UnitSphereSampler {
+    private static final class UnitSphereSampler2D extends UnitSphereSampler {
         /** Sampler used for generating the individual components of the vectors. */
         private final NormalizedGaussianSampler sampler;
 
@@ -123,7 +123,7 @@ public UnitSphereSampler withUniformRandomProvider(UniformRandomProvider rng) {
      * Sample uniformly from a 3D unit sphere.
      * This is a 3D specialisation of the UnitSphereSamplerND.
      */
-    private static class UnitSphereSampler3D extends UnitSphereSampler {
+    private static final class UnitSphereSampler3D extends UnitSphereSampler {
         /** Sampler used for generating the individual components of the vectors. */
         private final NormalizedGaussianSampler sampler;
 
@@ -159,7 +159,7 @@ public UnitSphereSampler withUniformRandomProvider(UniformRandomProvider rng) {
     /**
      * Sample uniformly from a ND unit sphere.
      */
-    private static class UnitSphereSamplerND extends UnitSphereSampler {
+    private static final class UnitSphereSamplerND extends UnitSphereSampler {
         /** Space dimension. */
         private final int dimension;
         /** Sampler used for generating the individual components of the vectors. */

commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/AhrensDieterMarsagliaTsangGammaSampler.java

@@ -116,7 +116,7 @@ public String toString() {
      *  Computing, 12, 223-246, 1974.
      * </blockquote>
      */
-    private static class AhrensDieterGammaSampler
+    private static final class AhrensDieterGammaSampler
         extends BaseGammaSampler {
 
         /** Inverse of "alpha". */
@@ -196,7 +196,7 @@ public SharedStateContinuousSampler withUniformRandomProvider(UniformRandomProvi
      *  Volume 26 Issue 3, September, 2000.
      * </blockquote>
      */
-    private static class MarsagliaTsangGammaSampler
+    private static final class MarsagliaTsangGammaSampler
         extends BaseGammaSampler {
 
         /** 1/3. */

commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/AliasMethodDiscreteSampler.java

@@ -171,7 +171,7 @@ public class AliasMethodDiscreteSampler
      *
      * <p>Sampling uses 1 or 2 calls to {@link UniformRandomProvider#nextInt()}.</p>
      */
-    private static class SmallTableAliasMethodDiscreteSampler extends AliasMethodDiscreteSampler {
+    private static final class SmallTableAliasMethodDiscreteSampler extends AliasMethodDiscreteSampler {
         /** The mask to isolate the lower bits. */
         private final int mask;
 

commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/ChengBetaSampler.java

@@ -136,7 +136,7 @@ protected double computeX(double w) {
      * Computes one sample using Cheng's BB algorithm, when beta distribution {@code alpha} and
      * {@code beta} shape parameters are both larger than 1.
      */
-    private static class ChengBBBetaSampler extends BaseChengBetaSampler {
+    private static final class ChengBBBetaSampler extends BaseChengBetaSampler {
         /** 1 + natural logarithm of 5. */
         private static final double LN_5_P1 = 1 + Math.log(5.0);
 
@@ -210,7 +210,7 @@ public SharedStateContinuousSampler withUniformRandomProvider(UniformRandomProvi
      * Computes one sample using Cheng's BC algorithm, when at least one of beta distribution
      * {@code alpha} or {@code beta} shape parameters is smaller than 1.
      */
-    private static class ChengBCBetaSampler extends BaseChengBetaSampler {
+    private static final class ChengBCBetaSampler extends BaseChengBetaSampler {
         /** 1/2. */
         private static final double ONE_HALF = 1d / 2;
         /** 1/4. */

commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/ContinuousUniformSampler.java

@@ -43,7 +43,7 @@ public class ContinuousUniformSampler
     /**
      * Specialization to sample from an open interval {@code (lo, hi)}.
      */
-    private static class OpenIntervalContinuousUniformSampler extends ContinuousUniformSampler {
+    private static final class OpenIntervalContinuousUniformSampler extends ContinuousUniformSampler {
         /**
          * @param rng Generator of uniformly distributed random numbers.
          * @param lo Lower bound.