IdentityPredicate.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.collections4.functors;

import java.io.Serializable;

import org.apache.commons.collections4.Predicate;

/**
 * Predicate implementation that returns true if the input is the same object
 * as the one stored in this predicate.
 *
 * @param <T> the type of the input to the predicate.
 * @since 3.0
 */
public final class IdentityPredicate<T> extends AbstractPredicate<T> implements Serializable {

    /** Serial version UID */
    private static final long serialVersionUID = -89901658494523293L;

    /**
     * Creates the identity predicate.
     *
     * @param <T> the type that the predicate queries
     * @param object  the object to compare to
     * @return the predicate
     */
    public static <T> Predicate<T> identityPredicate(final T object) {
        if (object == null) {
            return NullPredicate.<T>nullPredicate();
        }
        return new IdentityPredicate<>(object);
    }

    /** The value to compare to */
    private final T iValue;

    /**
     * Constructor that performs no validation.
     * Use {@code identityPredicate} if you want that.
     *
     * @param object  the object to compare to
     */
    public IdentityPredicate(final T object) {
        iValue = object;
    }

    /**
     * Gets the value.
     *
     * @return the value
     * @since 3.1
     */
    public T getValue() {
        return iValue;
    }

    /**
     * Evaluates the predicate returning true if the input object is identical to
     * the stored object.
     *
     * @param object  the input object
     * @return true if input is the same object as the stored value
     */
    @Override
    public boolean test(final T object) {
        return iValue == object;
    }

}