Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.reef.tang.util;
020
021import java.util.HashMap;
022import java.util.Map;
023
024public class MonotonicHashMap<T, U> extends HashMap<T, U> {
025  private static final long serialVersionUID = 1L;
026
027  @Override
028  public U put(final T key, final U value) {
029    final U old = super.get(key);
030    if (old != null) {
031      throw new IllegalArgumentException("Attempt to re-add: [" + key
032          + "] old value: " + old + " new value " + value);
033    }
034    return super.put(key, value);
035  }
036
037  @Override
038  public void putAll(final Map<? extends T, ? extends U> m) {
039    for (final T t : m.keySet()) {
040      if (containsKey(t)) {
041        put(t, m.get(t)); // guaranteed to throw.
042      }
043    }
044    for (final T t : m.keySet()) {
045      put(t, m.get(t));
046    }
047  }
048
049  @Override
050  public void clear() {
051    throw new UnsupportedOperationException();
052  }
053
054  @Override
055  public U remove(final Object o) {
056    throw new UnsupportedOperationException();
057  }
058}