Use a "static" instance rather than an anonymous one instantiated

on-the-fly.

src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java

@@ -20,9 +20,9 @@ package org.apache.commons.math3.ml.neuralnet;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Comparator;
 
 import org.apache.commons.math3.exception.NoDataException;
 import org.apache.commons.math3.ml.distance.DistanceMeasure;
@@ -137,13 +137,7 @@ public class MapUtils {
             list.add(new PairNeuronDouble(n, d));
         }
 
-        Collections.sort(list, new Comparator<PairNeuronDouble>() {
-            /** {@inheritDoc} */
-            @Override
-            public int compare(final PairNeuronDouble pn1, final PairNeuronDouble pn2) {
-                return Double.compare(pn1.getValue(), pn2.getValue());
-            }
-        });
+        Collections.sort(list, PairNeuronDouble.COMPARATOR);
 
         final int len = list.size();
         final Neuron[] sorted = new Neuron[len];
@@ -300,9 +294,19 @@ public class MapUtils {
      * Helper data structure holding a (Neuron, double) pair.
      */
     private static class PairNeuronDouble {
-        /** Key */
+        /** Comparator. */
+        static final Comparator<PairNeuronDouble> COMPARATOR
+            = new Comparator<PairNeuronDouble>() {
+            /** {@inheritDoc} */
+            @Override
+            public int compare(PairNeuronDouble o1,
+                               PairNeuronDouble o2) {
+                return Double.compare(o1.value, o2.value);
+            }
+        };
+        /** Key. */
         private final Neuron neuron;
-        /** Value */
+        /** Value. */
         private final double value;
 
         /**
@@ -319,11 +323,5 @@ public class MapUtils {
             return neuron;
         }
 
-        /** @return the value. */
-        public double getValue() {
-            return value;
-        }
-
     }
-
 }