    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.functors;
    018
    019import java.io.Serializable;
    020
    021import org.apache.commons.collections4.Predicate;
    022
    023/**
    024 * Predicate implementation that returns true if the input is the same object
    025 * as the one stored in this predicate.
    026 *
    027 * @param <T> the type of the input to the predicate.
    028 * @since 3.0
    029 */
    030public final class IdentityPredicate<T> extends AbstractPredicate<T> implements Serializable {
    031
    032    /** Serial version UID */
    033    private static final long serialVersionUID = -89901658494523293L;
    034
    035    /**
    036     * Creates the identity predicate.
    037     *
    038     * @param <T> the type that the predicate queries
    039     * @param object  the object to compare to
    040     * @return the predicate
    041     */
    042    public static <T> Predicate<T> identityPredicate(final T object) {
    043        if (object == null) {
    044            return NullPredicate.<T>nullPredicate();
    045        }
    046        return new IdentityPredicate<>(object);
    047    }
    048
    049    /** The value to compare to */
    050    private final T iValue;
    051
    052    /**
    053     * Constructor that performs no validation.
    054     * Use {@code identityPredicate} if you want that.
    055     *
    056     * @param object  the object to compare to
    057     */
    058    public IdentityPredicate(final T object) {
    059        iValue = object;
    060    }
    061
    062    /**
    063     * Gets the value.
    064     *
    065     * @return the value
    066     * @since 3.1
    067     */
    068    public T getValue() {
    069        return iValue;
    070    }
    071
    072    /**
    073     * Evaluates the predicate returning true if the input object is identical to
    074     * the stored object.
    075     *
    076     * @param object  the input object
    077     * @return true if input is the same object as the stored value
    078     */
    079    @Override
    080    public boolean test(final T object) {
    081        return iValue == object;
    082    }
    083
    084}