Applying Matt's patch with my modifications from LANG-588. Adds a Pair class to Lang.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@916098 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/lang3/Pair.java

@@ -0,0 +1,94 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.lang3;
+
+import java.io.IOException;
+import java.io.Serializable;
+
+import org.apache.commons.lang3.builder.HashCodeBuilder;
+
+/**
+ * A basic immutable Object pair.
+ * @since Lang 3.0
+ * @author Matt Benson
+ */
+public final class Pair<L, R> implements Serializable {
+    /** Serialization version */
+    private static final long serialVersionUID = 4954918890077093841L;
+
+    /** Left object */
+    public final L left;
+
+    /** Right object */
+    public final R right;
+
+    /**
+     * Create a new Pair instance.
+     * @param left
+     * @param right
+     */
+    public Pair(L left, R right) {
+        this.left = left;
+        this.right = right;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public boolean equals(Object obj) {
+        if (obj == this) {
+            return true;
+        }
+        if (obj instanceof Pair<?, ?> == false) {
+            return false;
+        }
+        Pair<?, ?> other = (Pair<?, ?>) obj;
+        return ObjectUtils.equals(left, other.left) && ObjectUtils.equals(right, other.right);
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public int hashCode() {
+        return new HashCodeBuilder().append(left).append(right).toHashCode();
+    }
+
+    /**
+     * Returns a String representation of the Pair in the form: (L,R)
+     */
+    public String toString() {
+        StringBuilder builder = new StringBuilder();
+        builder.append("(");
+        builder.append(left);
+        builder.append(",");
+        builder.append(right);
+        builder.append(")");
+        return builder.toString();
+    }
+
+    /**
+     * Static creation method for a Pair<L, R>.
+     * @param <L>
+     * @param <R>
+     * @param left
+     * @param right
+     * @return Pair<L, R>(left, right)
+     */
+    public static <L, R> Pair<L, R> of(L left, R right) {
+        return new Pair<L, R>(left, right);
+    }
+}

src/test/java/org/apache/commons/lang3/PairTest.java

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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.lang3;
+
+import static org.junit.Assert.*;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+
+import org.junit.Test;
+
+/**
+ * Test the Pair class.
+ * @author Matt Benson
+ */
+public class PairTest {
+
+    @Test
+    public void testBasic() throws Exception {
+        Pair<Integer, String> pair = new Pair<Integer, String>(0, "foo");
+        assertEquals(0, pair.left.intValue());
+        assertEquals("foo", pair.right);
+        Pair<Object, String> pair2 = new Pair<Object, String>(null, "bar");
+        assertNull(pair2.left);
+        assertEquals("bar", pair2.right);
+    }
+
+    @Test
+    public void testPairOf() throws Exception {
+        Pair<Integer, String> pair = Pair.of(0, "foo");
+        assertEquals(0, pair.left.intValue());
+        assertEquals("foo", pair.right);
+        Pair<Object, String> pair2 = Pair.of(null, "bar");
+        assertNull(pair2.left);
+        assertEquals("bar", pair2.right);
+    }
+
+    @Test
+    public void testEquals() throws Exception {
+        assertEquals(Pair.of(null, "foo"), Pair.of(null, "foo"));
+        assertFalse(Pair.of("foo", 0).equals(Pair.of("foo", null)));
+    }
+
+    @Test
+    public void testHashCode() throws Exception {
+        assertEquals(Pair.of(null, "foo").hashCode(), Pair.of(null, "foo").hashCode());
+    }
+
+    @Test
+    @SuppressWarnings("unchecked")
+    public void testSerialization() throws Exception {
+        Pair<Integer, String> origPair = Pair.of(0, "foo");
+        ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        ObjectOutputStream out = new ObjectOutputStream(baos);
+        out.writeObject(origPair);
+        Pair<Integer, String> deserializedPair = (Pair<Integer, String>) new ObjectInputStream(
+                new ByteArrayInputStream(baos.toByteArray())).readObject();
+        assertEquals(origPair, deserializedPair);
+        assertEquals(origPair.hashCode(), deserializedPair.hashCode());
+    }
+}