    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  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 */
    017package org.apache.commons.collections4.set;
    018
    019import java.util.Set;
    020
    021import org.apache.commons.collections4.Predicate;
    022import org.apache.commons.collections4.collection.PredicatedCollection;
    023
    024/**
    025 * Decorates another {@code Set} to validate that all additions
    026 * match a specified predicate.
    027 * <p>
    028 * This set exists to provide validation for the decorated set.
    029 * It is normally created to decorate an empty set.
    030 * If an object cannot be added to the set, an IllegalArgumentException is thrown.
    031 * </p>
    032 * <p>
    033 * One usage would be to ensure that no null entries are added to the set.
    034 * </p>
    035 * <pre>Set set = PredicatedSet.decorate(new HashSet(), NotNullPredicate.INSTANCE);</pre>
    036 * <p>
    037 * This class is Serializable from Commons Collections 3.1.
    038 * </p>
    039 *
    040 * @param <E> the type of the elements in this set
    041 * @since 3.0
    042 */
    043public class PredicatedSet<E> extends PredicatedCollection<E> implements Set<E> {
    044
    045    /** Serialization version */
    046    private static final long serialVersionUID = -684521469108685117L;
    047
    048    /**
    049     * Factory method to create a predicated (validating) set.
    050     * <p>
    051     * If there are any elements already in the set being decorated, they
    052     * are validated.
    053     *
    054     * @param <E> the element type
    055     * @param set  the set to decorate, must not be null
    056     * @param predicate  the predicate to use for validation, must not be null
    057     * @return a decorated set
    058     * @throws NullPointerException if set or predicate is null
    059     * @throws IllegalArgumentException if the set contains invalid elements
    060     * @since 4.0
    061     */
    062    public static <E> PredicatedSet<E> predicatedSet(final Set<E> set, final Predicate<? super E> predicate) {
    063        return new PredicatedSet<>(set, predicate);
    064    }
    065
    066    /**
    067     * Constructor that wraps (not copies).
    068     * <p>
    069     * If there are any elements already in the set being decorated, they
    070     * are validated.
    071     *
    072     * @param set  the set to decorate, must not be null
    073     * @param predicate  the predicate to use for validation, must not be null
    074     * @throws NullPointerException if set or predicate is null
    075     * @throws IllegalArgumentException if the set contains invalid elements
    076     */
    077    protected PredicatedSet(final Set<E> set, final Predicate<? super E> predicate) {
    078        super(set, predicate);
    079    }
    080
    081    /**
    082     * Gets the set being decorated.
    083     *
    084     * @return the decorated set
    085     */
    086    @Override
    087    protected Set<E> decorated() {
    088        return (Set<E>) super.decorated();
    089    }
    090
    091    @Override
    092    public boolean equals(final Object object) {
    093        return object == this || decorated().equals(object);
    094    }
    095
    096    @Override
    097    public int hashCode() {
    098        return decorated().hashCode();
    099    }
    100
    101}