001/* 002 * Copyright (C) 2007 The Guava 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 * http://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 com.google.common.collect; 018 019import com.google.common.annotations.GwtCompatible; 020import com.google.errorprone.annotations.DoNotMock; 021import java.util.Map; 022import javax.annotation.CheckForNull; 023import org.checkerframework.checker.nullness.qual.Nullable; 024 025/** 026 * An object representing the differences between two maps. 027 * 028 * @author Kevin Bourrillion 029 * @since 2.0 030 */ 031@DoNotMock("Use Maps.difference") 032@GwtCompatible 033public interface MapDifference<K extends @Nullable Object, V extends @Nullable Object> { 034 /** 035 * Returns {@code true} if there are no differences between the two maps; that is, if the maps are 036 * equal. 037 */ 038 boolean areEqual(); 039 040 /** 041 * Returns an unmodifiable map containing the entries from the left map whose keys are not present 042 * in the right map. 043 */ 044 Map<K, V> entriesOnlyOnLeft(); 045 046 /** 047 * Returns an unmodifiable map containing the entries from the right map whose keys are not 048 * present in the left map. 049 */ 050 Map<K, V> entriesOnlyOnRight(); 051 052 /** 053 * Returns an unmodifiable map containing the entries that appear in both maps; that is, the 054 * intersection of the two maps. 055 */ 056 Map<K, V> entriesInCommon(); 057 058 /** 059 * Returns an unmodifiable map describing keys that appear in both maps, but with different 060 * values. 061 */ 062 Map<K, ValueDifference<V>> entriesDiffering(); 063 064 /** 065 * Compares the specified object with this instance for equality. Returns {@code true} if the 066 * given object is also a {@code MapDifference} and the values returned by the {@link 067 * #entriesOnlyOnLeft()}, {@link #entriesOnlyOnRight()}, {@link #entriesInCommon()} and {@link 068 * #entriesDiffering()} of the two instances are equal. 069 */ 070 @Override 071 boolean equals(@CheckForNull Object object); 072 073 /** 074 * Returns the hash code for this instance. This is defined as the hash code of 075 * 076 * <pre>{@code 077 * Arrays.asList(entriesOnlyOnLeft(), entriesOnlyOnRight(), 078 * entriesInCommon(), entriesDiffering()) 079 * }</pre> 080 */ 081 @Override 082 int hashCode(); 083 084 /** 085 * A difference between the mappings from two maps with the same key. The {@link #leftValue} and 086 * {@link #rightValue} are not equal, and one but not both of them may be null. 087 * 088 * @since 2.0 089 */ 090 @DoNotMock("Use Maps.difference") 091 interface ValueDifference<V extends @Nullable Object> { 092 /** Returns the value from the left map (possibly null). */ 093 @ParametricNullness 094 V leftValue(); 095 096 /** Returns the value from the right map (possibly null). */ 097 @ParametricNullness 098 V rightValue(); 099 100 /** 101 * Two instances are considered equal if their {@link #leftValue()} values are equal and their 102 * {@link #rightValue()} values are also equal. 103 */ 104 @Override 105 boolean equals(@CheckForNull Object other); 106 107 /** 108 * The hash code equals the value {@code Arrays.asList(leftValue(), rightValue()).hashCode()}. 109 */ 110 @Override 111 int hashCode(); 112 } 113}