Java API for mojo system.

mojo/public/java/src/org/chromium/mojo/system/Pair.java

Index: mojo/public/java/src/org/chromium/mojo/system/Pair.java
diff --git a/mojo/public/java/src/org/chromium/mojo/system/Pair.java b/mojo/public/java/src/org/chromium/mojo/system/Pair.java
new file mode 100644
index 0000000000000000000000000000000000000000..c302aed680819645064e4cbdd94eb02e1fd52895
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+++ b/mojo/public/java/src/org/chromium/mojo/system/Pair.java
@@ -0,0 +1,61 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.mojo.system;
+
+import java.util.Objects;
+
+/**
+ * A pair of object.
+ *
+ * @param <F> Type of the first element.
+ * @param <S> Type of the second element.
+ */
+public class Pair<F, S> {

[bulach, 2014/04/17 13:15:42]

@viettrungluu: could we discuss about the ultimate goals for mojo? :)
qsr said that ultimately we want to be run-time independent.
it seems a bit of an overkill, since android does provide a "Pair" class.. are
we planning to run this on any other run time?

I mean, it'd be nice to have and all that :) but objectively, saving binary size
is a big goal for chrome on android: if we could save now in exchange for a
future possibility of using other runtimes, I'd suggest choosing to save
precious bytes now... wdyt?

+
+    public final F first;
+    public final S second;
+
+    /**
+     * Dedicated constructor.
+     *
+     * @param first the first element of the pair.
+     * @param second the second element of the pair.
+     */
+    public Pair(F first, S second) {
+        this.first = first;
+        this.second = second;
+    }
+
+    /**
+     * @see Object#equals(Object)
+     */
+    @Override
+    public boolean equals(Object o) {
+        if (!(o instanceof Pair)) {
+            return false;
+        }
+        Pair<?, ?> p = (Pair<?, ?>) o;
+        return Objects.equals(p.first, first) && Objects.equals(p.second, second);
+    }
+
+    /**
+     * @see Object#hashCode()
+     */
+    @Override
+    public int hashCode() {
+        return (first == null ? 0 : first.hashCode()) ^ (second == null ? 0 : second.hashCode());
+    }
+
+    /**
+     * Helper method for creating a pair.
+     *
+     * @param a the first element of the pair.
+     * @param b the second element of the pair.
+     * @return the pair containing a and b.
+     */
+    public static <A, B, C extends A, D extends B> Pair<A, B> create(C a, D b) {
+        return new Pair<A, B>(a, b);
+    }
+}