Merge pull request #379 from Serrof/issue-378

use Java 8 features instead of <=7

Author: Serrof

hipparchus-clustering/src/main/java/org/hipparchus/clustering/FuzzyKMeansClusterer.java

@@ -300,7 +300,7 @@ public List<CentroidCluster<T>> cluster(final Collection<T> dataPoints)
         // there is at least one point
         final int pointDimension = points.get(0).getPoint().length;
         for (int i = 0; i < k; i++) {
-            clusters.add(new CentroidCluster<T>(new DoublePoint(new double[pointDimension])));
+            clusters.add(new CentroidCluster<>(new DoublePoint(new double[pointDimension])));
         }
 
         int iteration = 0;
@@ -338,7 +338,7 @@ private void updateClusterCenters() {
                 i++;
             }
             MathArrays.scaleInPlace(1.0 / sum, arr);
-            newClusters.add(new CentroidCluster<T>(new DoublePoint(arr)));
+            newClusters.add(new CentroidCluster<>(new DoublePoint(arr)));
             j++;
         }
         clusters.clear();

hipparchus-clustering/src/main/java/org/hipparchus/clustering/KMeansPlusPlusClusterer.java

@@ -241,7 +241,7 @@ public List<CentroidCluster<T>> cluster(final Collection<T> points)
                 } else {
                     newCenter = centroidOf(cluster.getPoints(), cluster.getCenter().getPoint().length);
                 }
-                newClusters.add(new CentroidCluster<T>(newCenter));
+                newClusters.add(new CentroidCluster<>(newCenter));
             }
             int changes = assignPointsToClusters(newClusters, points, assignments);
             clusters = newClusters;
@@ -292,7 +292,7 @@ private List<CentroidCluster<T>> chooseInitialCenters(final Collection<T> points
 
         // Convert to list for indexed access. Make it unmodifiable, since removal of items
         // would screw up the logic of this method.
-        final List<T> pointList = Collections.unmodifiableList(new ArrayList<T> (points));
+        final List<T> pointList = Collections.unmodifiableList(new ArrayList<>(points));
 
         // The number of points in the list.
         final int numPoints = pointList.size();
@@ -309,7 +309,7 @@ private List<CentroidCluster<T>> chooseInitialCenters(final Collection<T> points
 
         final T firstPoint = pointList.get(firstPointIndex);
 
-        resultSet.add(new CentroidCluster<T>(firstPoint));
+        resultSet.add(new CentroidCluster<>(firstPoint));
 
         // Must mark it as taken
         taken[firstPointIndex] = true;
@@ -376,7 +376,7 @@ private List<CentroidCluster<T>> chooseInitialCenters(final Collection<T> points
 
                 final T p = pointList.get(nextPointIndex);
 
-                resultSet.add(new CentroidCluster<T> (p));
+                resultSet.add(new CentroidCluster<>(p));
 
                 // Mark it as taken.
                 taken[nextPointIndex] = true;

hipparchus-clustering/src/main/java/org/hipparchus/clustering/MultiKMeansPlusPlusClusterer.java

@@ -52,7 +52,7 @@ public class MultiKMeansPlusPlusClusterer<T extends Clusterable> extends Cluster
      */
     public MultiKMeansPlusPlusClusterer(final KMeansPlusPlusClusterer<T> clusterer,
                                         final int numTrials) {
-        this(clusterer, numTrials, new SumOfClusterVariances<T>(clusterer.getDistanceMeasure()));
+        this(clusterer, numTrials, new SumOfClusterVariances<>(clusterer.getDistanceMeasure()));
     }
 
     /** Build a clusterer.

hipparchus-core/src/main/java/org/hipparchus/analysis/FunctionUtils.java

@@ -327,7 +327,7 @@ public static double[] sample(UnivariateFunction f, double min, double max, int
         if (n <= 0) {
             throw new MathIllegalArgumentException(
                     LocalizedCoreFormats.NOT_POSITIVE_NUMBER_OF_SAMPLES,
-                    Integer.valueOf(n));
+                    n);
         }
         if (min >= max) {
             throw new MathIllegalArgumentException(LocalizedCoreFormats.NUMBER_TOO_LARGE_BOUND_EXCLUDED,

hipparchus-core/src/main/java/org/hipparchus/analysis/differentiation/SparseGradient.java

@@ -160,12 +160,7 @@ public SparseGradient add(final SparseGradient a) {
         final SparseGradient out = new SparseGradient(value + a.value, derivatives);
         for (Map.Entry<Integer, Double> entry : a.derivatives.entrySet()) {
             final int id = entry.getKey();
-            final Double old = out.derivatives.get(id);
-            if (old == null) {
-                out.derivatives.put(id, entry.getValue());
-            } else {
-                out.derivatives.put(id, old + entry.getValue());
-            }
+            out.derivatives.merge(id, entry.getValue(), Double::sum);
         }
 
         return out;
@@ -187,12 +182,7 @@ public void addInPlace(final SparseGradient a) {
         value += a.value;
         for (final Map.Entry<Integer, Double> entry : a.derivatives.entrySet()) {
             final int id = entry.getKey();
-            final Double old = derivatives.get(id);
-            if (old == null) {
-                derivatives.put(id, entry.getValue());
-            } else {
-                derivatives.put(id, old + entry.getValue());
-            }
+            derivatives.merge(id, entry.getValue(), Double::sum);
         }
     }
 
@@ -224,12 +214,7 @@ public SparseGradient multiply(final SparseGradient a) {
         }
         for (Map.Entry<Integer, Double> entry : a.derivatives.entrySet()) {
             final int id = entry.getKey();
-            final Double old = out.derivatives.get(id);
-            if (old == null) {
-                out.derivatives.put(id, value * entry.getValue());
-            } else {
-                out.derivatives.put(id, old + value * entry.getValue());
-            }
+            out.derivatives.merge(id, value * entry.getValue(), Double::sum);
         }
         return out;
     }
@@ -248,17 +233,10 @@ public SparseGradient multiply(final SparseGradient a) {
      */
     public void multiplyInPlace(final SparseGradient a) {
         // Derivatives.
-        for (Map.Entry<Integer, Double> entry : derivatives.entrySet()) {
-            derivatives.put(entry.getKey(), a.value * entry.getValue());
-        }
+        derivatives.replaceAll((k, v) -> a.value * v);
         for (Map.Entry<Integer, Double> entry : a.derivatives.entrySet()) {
             final int id = entry.getKey();
-            final Double old = derivatives.get(id);
-            if (old == null) {
-                derivatives.put(id, value * entry.getValue());
-            } else {
-                derivatives.put(id, old + value * entry.getValue());
-            }
+            derivatives.merge(id, value * entry.getValue(), Double::sum);
         }
         value *= a.value;
     }

hipparchus-core/src/main/java/org/hipparchus/analysis/interpolation/LoessInterpolator.java

@@ -451,8 +451,8 @@ private static double tricube(final double x) {
      * if one of the values is not a finite real number.
      */
     private static void checkAllFiniteReal(final double[] values) {
-        for (int i = 0; i < values.length; i++) {
-            MathUtils.checkFinite(values[i]);
+        for (double value : values) {
+            MathUtils.checkFinite(value);
         }
     }
 }

hipparchus-core/src/main/java/org/hipparchus/analysis/solvers/LaguerreSolver.java

@@ -158,9 +158,9 @@ private double laguerre(double lo, double hi) {
             double r = Double.NaN;
             // Solve all roots and select the one we are seeking.
             Complex[] root = complexSolver.solveAll(c, initial);
-            for (int i = 0; i < root.length; i++) {
-                if (complexSolver.isRoot(lo, hi, root[i])) {
-                    r = root[i].getReal();
+            for (Complex complex : root) {
+                if (complexSolver.isRoot(lo, hi, complex)) {
+                    r = complex.getReal();
                     break;
                 }
             }

hipparchus-core/src/main/java/org/hipparchus/complex/RootsOfUnity.java

@@ -167,9 +167,9 @@ public double getReal(int k)
             if ((k < 0) || (k >= omegaCount)) {
                 throw new MathIllegalArgumentException(
                                                        LocalizedCoreFormats.OUT_OF_RANGE_ROOT_OF_UNITY_INDEX,
-                                                       Integer.valueOf(k),
-                                                       Integer.valueOf(0),
-                                                       Integer.valueOf(omegaCount - 1));
+                        k,
+                        0,
+                        omegaCount - 1);
             }
 
             return omegaReal[k];
@@ -195,9 +195,9 @@ public double getImaginary(int k)
             if ((k < 0) || (k >= omegaCount)) {
                 throw new MathIllegalArgumentException(
                                                        LocalizedCoreFormats.OUT_OF_RANGE_ROOT_OF_UNITY_INDEX,
-                                                       Integer.valueOf(k),
-                                                       Integer.valueOf(0),
-                                                       Integer.valueOf(omegaCount - 1));
+                        k,
+                        0,
+                        omegaCount - 1);
             }
 
             return isCounterClockWise ? omegaImaginaryCounterClockwise[k] :

hipparchus-core/src/main/java/org/hipparchus/distribution/continuous/EnumeratedRealDistribution.java

@@ -77,7 +77,7 @@ public EnumeratedRealDistribution(final double[] data) {
         int index = 0;
         for (Entry<Double, Integer> entry : dataMap.entrySet()) {
             values[index] = entry.getKey();
-            probabilities[index] = entry.getValue().intValue() / denom;
+            probabilities[index] = entry.getValue() / denom;
             index++;
         }
         innerDistribution =

hipparchus-core/src/main/java/org/hipparchus/distribution/discrete/EnumeratedIntegerDistribution.java

@@ -91,7 +91,7 @@ public EnumeratedIntegerDistribution(final int[] data) {
         int index = 0;
         for (Entry<Integer, Integer> entry : dataMap.entrySet()) {
             values[index] = entry.getKey();
-            probabilities[index] = entry.getValue().intValue() / denom;
+            probabilities[index] = entry.getValue() / denom;
             index++;
         }
         innerDistribution =