Update #0 - First Release

sources/main/java/com/google/common/collect/AbstractMapEntry.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2007 The Guava Authors
+ *
+ * Licensed 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 com.google.common.collect;
+
+import java.util.Map.Entry;
+
+import javax.annotation.Nullable;
+
+import com.google.common.annotations.GwtCompatible;
+import com.google.common.base.Objects;
+
+/**
+ * Implementation of the {@code equals}, {@code hashCode}, and {@code toString}
+ * methods of {@code Entry}.
+ *
+ * @author Jared Levy
+ */
+@GwtCompatible
+abstract class AbstractMapEntry<K, V> implements Entry<K, V> {
+
+	@Override
+	public abstract K getKey();
+
+	@Override
+	public abstract V getValue();
+
+	@Override
+	public V setValue(V value) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean equals(@Nullable Object object) {
+		if (object instanceof Entry) {
+			Entry<?, ?> that = (Entry<?, ?>) object;
+			return Objects.equal(this.getKey(), that.getKey()) && Objects.equal(this.getValue(), that.getValue());
+		}
+		return false;
+	}
+
+	@Override
+	public int hashCode() {
+		K k = getKey();
+		V v = getValue();
+		return ((k == null) ? 0 : k.hashCode()) ^ ((v == null) ? 0 : v.hashCode());
+	}
+
+	/**
+	 * Returns a string representation of the form {@code {key}={value}}.
+	 */
+	@Override
+	public String toString() {
+		return getKey() + "=" + getValue();
+	}
+}