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; 023import org.springframework.util.Assert; 024 025/** 026 * A decorator for a comparator, with an "ascending" flag denoting 027 * whether comparison results should be treated in forward (standard 028 * ascending) order or flipped for reverse (descending) order. 029 * 030 * @author Keith Donald 031 * @author Juergen Hoeller 032 * @since 1.2.2 033 * @param <T> the type of objects that may be compared by this comparator 034 * @deprecated as of Spring Framework 5.0, in favor of the standard JDK 8 035 * {@link Comparator#reversed()} 036 */ 037@Deprecated 038@SuppressWarnings("serial") 039public class InvertibleComparator<T> implements Comparator<T>, Serializable { 040 041 private final Comparator<T> comparator; 042 043 private boolean ascending = true; 044 045 046 /** 047 * Create an InvertibleComparator that sorts ascending by default. 048 * For the actual comparison, the specified Comparator will be used. 049 * @param comparator the comparator to decorate 050 */ 051 public InvertibleComparator(Comparator<T> comparator) { 052 Assert.notNull(comparator, "Comparator must not be null"); 053 this.comparator = comparator; 054 } 055 056 /** 057 * Create an InvertibleComparator that sorts based on the provided order. 058 * For the actual comparison, the specified Comparator will be used. 059 * @param comparator the comparator to decorate 060 * @param ascending the sort order: ascending (true) or descending (false) 061 */ 062 public InvertibleComparator(Comparator<T> comparator, boolean ascending) { 063 Assert.notNull(comparator, "Comparator must not be null"); 064 this.comparator = comparator; 065 setAscending(ascending); 066 } 067 068 069 /** 070 * Specify the sort order: ascending (true) or descending (false). 071 */ 072 public void setAscending(boolean ascending) { 073 this.ascending = ascending; 074 } 075 076 /** 077 * Return the sort order: ascending (true) or descending (false). 078 */ 079 public boolean isAscending() { 080 return this.ascending; 081 } 082 083 /** 084 * Invert the sort order: ascending -> descending or 085 * descending -> ascending. 086 */ 087 public void invertOrder() { 088 this.ascending = !this.ascending; 089 } 090 091 092 @Override 093 public int compare(T o1, T o2) { 094 int result = this.comparator.compare(o1, o2); 095 if (result != 0) { 096 // Invert the order if it is a reverse sort. 097 if (!this.ascending) { 098 if (Integer.MIN_VALUE == result) { 099 result = Integer.MAX_VALUE; 100 } 101 else { 102 result *= -1; 103 } 104 } 105 return result; 106 } 107 return 0; 108 } 109 110 @Override 111 @SuppressWarnings("unchecked") 112 public boolean equals(@Nullable Object other) { 113 if (this == other) { 114 return true; 115 } 116 if (!(other instanceof InvertibleComparator)) { 117 return false; 118 } 119 InvertibleComparator<T> otherComp = (InvertibleComparator<T>) other; 120 return (this.comparator.equals(otherComp.comparator) && this.ascending == otherComp.ascending); 121 } 122 123 @Override 124 public int hashCode() { 125 return this.comparator.hashCode(); 126 } 127 128 @Override 129 public String toString() { 130 return "InvertibleComparator: [" + this.comparator + "]; ascending=" + this.ascending; 131 } 132 133}