MATH-810

Added new accessors.


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1357004 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/math3/util/Pair.java

@@ -39,8 +39,8 @@ public class Pair<K, V> {
      * Create an entry representing a mapping from the specified key to the
      * specified value.
      *
-     * @param k Key.
-     * @param v Value.
+     * @param k Key (first element of the pair).
+     * @param v Value (second element of the pair).
      */
     public Pair(K k, V v) {
         key = k;
@@ -59,7 +59,7 @@ public class Pair<K, V> {
     /**
      * Get the key.
      *
-     * @return the key.
+     * @return the key (first element of the pair).
      */
     public K getKey() {
         return key;
@@ -68,12 +68,30 @@ public class Pair<K, V> {
     /**
      * Get the value.
      *
-     * @return the value.
+     * @return the value (second element of the pair).
      */
     public V getValue() {
         return value;
     }
 
+    /**
+     * Get the first element of the pair.
+     *
+     * @return the first element of the pair.
+     */
+    public K getFirst() {
+        return key;
+    }
+
+    /**
+     * Get the second element of the pair.
+     *
+     * @return the second element of the pair.
+     */
+    public V getSecond() {
+        return value;
+    }
+
     /**
      * Compare the specified object with this entry for equality.
      *

src/test/java/org/apache/commons/math3/util/PairTest.java

@@ -29,6 +29,17 @@ public class PairTest {
         Assert.assertEquals(new Double(2), p.getValue(), Math.ulp(1d));
     }
 
+    @Test
+    public void testAccessor2() {
+        final Pair<Integer, Double> p
+            = new Pair<Integer, Double>(new Integer(1), new Double(2));
+
+        // Check that both APIs refer to the same data.
+
+        Assert.assertTrue(p.getFirst() == p.getKey());
+        Assert.assertTrue(p.getSecond() == p.getValue());
+    }
+
     @Test
     public void testEquals() {
         Pair<Integer, Double> p1 = new Pair<Integer, Double>(null, null);