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.Arrays;
022import java.util.Collection;
023import java.util.HashSet;
024
025public class MonotonicHashSet<T> extends HashSet<T> {
026  private static final long serialVersionUID = 1L;
027
028  public MonotonicHashSet() {
029    super();
030  }
031
032  public MonotonicHashSet(final Collection<T> c) {
033    super(c);
034  }
035
036  @SafeVarargs
037  public MonotonicHashSet(final T... c) {
038    super(Arrays.asList(c));
039  }
040
041  @Override
042  public boolean add(final T e) {
043    if (super.contains(e)) {
044      throw new IllegalArgumentException("Attempt to re-add " + e
045          + " to MonotonicSet!");
046    }
047    return super.add(e);
048  }
049
050  @Override
051  public void clear() {
052    throw new UnsupportedOperationException("Attempt to clear MonotonicSet!");
053  }
054
055  @Override
056  public boolean remove(final Object o) {
057    throw new UnsupportedOperationException("Attempt to remove " + o
058        + " from MonotonicSet!");
059  }
060
061  @Override
062  public boolean removeAll(final Collection<?> c) {
063    throw new UnsupportedOperationException(
064        "removeAll() doesn't make sense for MonotonicSet!");
065  }
066
067  @Override
068  public boolean retainAll(final Collection<?> c) {
069    throw new UnsupportedOperationException(
070        "retainAll() doesn't make sense for MonotonicSet!");
071  }
072
073  @Override
074  public boolean addAll(final Collection<? extends T> c) {
075    for (final T t : c) {
076      add(t);
077    }
078    return c.size() != 0;
079  }
080
081  public boolean addAllIgnoreDuplicates(final Collection<? extends T> c) {
082    boolean ret = false;
083    for (final T t : c) {
084      if (!contains(t)) {
085        add(t);
086        ret = true;
087      }
088    }
089    return ret;
090  }
091}