001/*
002 * Copyright 2002-2018 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.util.comparator;
018
019import java.io.Serializable;
020import java.util.Comparator;
021
022import org.springframework.lang.Nullable;
023
024/**
025 * A {@link Comparator} for {@link Boolean} objects that can sort either
026 * {@code true} or {@code false} first.
027 *
028 * @author Keith Donald
029 * @since 1.2.2
030 */
031@SuppressWarnings("serial")
032public class BooleanComparator implements Comparator<Boolean>, Serializable {
033
034        /**
035         * A shared default instance of this comparator,
036         * treating {@code true} lower than {@code false}.
037         */
038        public static final BooleanComparator TRUE_LOW = new BooleanComparator(true);
039
040        /**
041         * A shared default instance of this comparator,
042         * treating {@code true} higher than {@code false}.
043         */
044        public static final BooleanComparator TRUE_HIGH = new BooleanComparator(false);
045
046
047        private final boolean trueLow;
048
049
050        /**
051         * Create a BooleanComparator that sorts boolean values based on
052         * the provided flag.
053         * <p>Alternatively, you can use the default shared instances:
054         * {@code BooleanComparator.TRUE_LOW} and
055         * {@code BooleanComparator.TRUE_HIGH}.
056         * @param trueLow whether to treat true as lower or higher than false
057         * @see #TRUE_LOW
058         * @see #TRUE_HIGH
059         */
060        public BooleanComparator(boolean trueLow) {
061                this.trueLow = trueLow;
062        }
063
064
065        @Override
066        public int compare(Boolean v1, Boolean v2) {
067                return (v1 ^ v2) ? ((v1 ^ this.trueLow) ? 1 : -1) : 0;
068        }
069
070
071        @Override
072        public boolean equals(@Nullable Object other) {
073                return (this == other || (other instanceof BooleanComparator &&
074                                this.trueLow == ((BooleanComparator) other).trueLow));
075        }
076
077        @Override
078        public int hashCode() {
079                return getClass().hashCode() * (this.trueLow ? -1 : 1);
080        }
081
082        @Override
083        public String toString() {
084                return "BooleanComparator: " + (this.trueLow ? "true low" : "true high");
085        }
086
087}