[New] Added a DefaultedHashMap for default values on unmapped keys

src/main/java/ch/eitchnet/utils/collections/DefaultedHashMap.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2015 Robert von Burg <eitch@eitchnet.ch>
+ * 
+ * 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 ch.eitchnet.utils.collections;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * @author Robert von Burg <eitch@eitchnet.ch>
+ */
+public class DefaultedHashMap<K, V> extends HashMap<K, V> {
+
+	private static final long serialVersionUID = 1L;
+	private V defaultValue;
+
+	/**
+	 * Constructs this {@link Map} instance to have a default value on inexistent keys
+	 * 
+	 * @param defaultValue
+	 *            the default to return if a key is not mapped
+	 */
+	public DefaultedHashMap(V defaultValue) {
+		this.defaultValue = defaultValue;
+	}
+
+	@Override
+	public V get(Object key) {
+		return getOrDefault(key, this.defaultValue);
+	}
+}

src/test/java/ch/eitchnet/utils/collections/DefaultedHashMapTest.java

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+/*
+ * Copyright 2015 Robert von Burg <eitch@eitchnet.ch>
+ * 
+ * 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 ch.eitchnet.utils.collections;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.util.Map;
+
+import org.junit.Before;
+import org.junit.Test;
+
+/**
+ * @author Robert von Burg <eitch@eitchnet.ch>
+ */
+public class DefaultedHashMapTest {
+
+	private Map<String, String> map;
+
+	@Before
+	public void setUp() {
+		this.map = new DefaultedHashMap<String, String>("foobar");
+		this.map.put("foo", "foofoo");
+	}
+
+	@Test
+	public void shouldReturnMappedValue() {
+		assertTrue(this.map.containsKey("foo"));
+		assertEquals("foofoo", this.map.get("foo"));
+	}
+
+	@Test
+	public void shouldReturnDefaultValue() {
+		assertFalse(this.map.containsKey("bar"));
+		assertEquals("foobar", this.map.get("bar"));
+	}
+}