From 4a1708d2e180b25b310f664cfbdfa8434d7ce1c6 Mon Sep 17 00:00:00 2001
From: Luc Maisonobe <luc@apache.org>
Date: Wed, 4 Nov 2015 14:07:22 +0100
Subject: [PATCH] PairNeuronDouble should not implement Comparable.

As the purpose was only to sort neurons according to an associated
value, using an explicit comparator is simpler. Implementing Comparable
induces also implementing equals and hashcode which are not really
meaningful. They are nevertheless required by our code quality checking
tools.
---
 .../commons/math3/ml/neuralnet/MapUtils.java  | 33 ++++++-------------
 1 file changed, 10 insertions(+), 23 deletions(-)

diff --git a/src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java b/src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java
index 6ef93270b..afafa8b14 100644
--- a/src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java
+++ b/src/main/java/org/apache/commons/math3/ml/neuralnet/MapUtils.java
@@ -20,6 +20,7 @@ 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;
 
@@ -136,7 +137,13 @@ public class MapUtils {
             list.add(new PairNeuronDouble(n, d));
         }
 
-        Collections.sort(list);
+        Collections.sort(list, new Comparator<PairNeuronDouble>() {
+            /** {@inheritDoc} */
+            @Override
+            public int compare(final PairNeuronDouble pn1, final PairNeuronDouble pn2) {
+                return Double.compare(pn1.getValue(), pn2.getValue());
+            }
+        });
 
         final int len = list.size();
         final Neuron[] sorted = new Neuron[len];
@@ -292,7 +299,7 @@ public class MapUtils {
     /**
      * Helper data structure holding a (Neuron, double) pair.
      */
-    private static class PairNeuronDouble implements Comparable<PairNeuronDouble> {
+    private static class PairNeuronDouble {
         /** Key */
         private final Neuron neuron;
         /** Value */
@@ -317,26 +324,6 @@ public class MapUtils {
             return value;
         }
 
-        /** {@inheritDoc} */
-        public int compareTo(PairNeuronDouble other) {
-            return Double.compare(this.value, other.value);
-        }
-
-        /** {@inheritDoc} */
-        @Override
-        public boolean equals(Object other) {
-            if (!(other instanceof PairNeuronDouble)) {
-                return false;
-            }
-            return Double.doubleToRawLongBits(value) ==
-                   Double.doubleToRawLongBits(((PairNeuronDouble) other).value);
-        }
-
-        /** {@inheritDoc} */
-        @Override
-        public int hashCode() {
-            return Double.valueOf(value).hashCode();
-        }
-
     }
+
 }