001/*-------------------------------------------------------------------------+
002|                                                                          |
003| Copyright (c) 2005-2019 The ConQAT Project                               |
004|                                                                          |
005| Licensed under the Apache License, Version 2.0 (the "License");          |
006| you may not use this file except in compliance with the License.         |
007| You may obtain a copy of the License at                                  |
008|                                                                          |
009|    http://www.apache.org/licenses/LICENSE-2.0                            |
010|                                                                          |
011| Unless required by applicable law or agreed to in writing, software      |
012| distributed under the License is distributed on an "AS IS" BASIS,        |
013| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
014| See the License for the specific language governing permissions and      |
015| limitations under the License.                                           |
016|                                                                          |
017+-------------------------------------------------------------------------*/
018package org.conqat.lib.commons.collections;
019
020import java.util.LinkedHashMap;
021import java.util.Map.Entry;
022
023/**
024 * A set with a limited size. Old elements exceeding this size are removed using
025 * a least recently inserted strategy.
026 */
027public class BoundedSet<E> extends MapBackedSetBase<E> {
028
029        /**
030         * Constructor.
031         * 
032         * @param maxSize
033         *            the set will never have more than this number of elements. If more
034         *            are inserted, the oldest inserted ones are removed.
035         */
036        public BoundedSet(int maxSize) {
037                super(new LinkedHashMap<E, Object>() {
038
039                        private static final long serialVersionUID = 1L;
040
041                        @Override
042                        protected boolean removeEldestEntry(Entry<E, Object> eldest) {
043                                return size() > maxSize;
044                        }
045                });
046        }
047}