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 * https://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.lang3.tuple; 018 019import java.io.Serializable; 020import java.util.Objects; 021 022import org.apache.commons.lang3.builder.CompareToBuilder; 023 024/** 025 * A triple consisting of three elements. 026 * 027 * <p>This class is an abstract implementation defining the basic API. 028 * It refers to the elements as 'left', 'middle' and 'right'.</p> 029 * 030 * <p>Subclass implementations may be mutable or immutable. 031 * However, there is no restriction on the type of the stored objects that may be stored. 032 * If mutable objects are stored in the triple, then the triple itself effectively becomes mutable.</p> 033 * 034 * @param <L> the left element type. 035 * @param <M> the middle element type. 036 * @param <R> the right element type. 037 * @since 3.2 038 */ 039public abstract class Triple<L, M, R> implements Comparable<Triple<L, M, R>>, Serializable { 040 041 /** Serialization version */ 042 private static final long serialVersionUID = 1L; 043 044 /** 045 * An empty array. 046 * <p> 047 * Consider using {@link #emptyArray()} to avoid generics warnings. 048 * </p> 049 * 050 * @since 3.10 051 */ 052 public static final Triple<?, ?, ?>[] EMPTY_ARRAY = {}; 053 054 /** 055 * Returns the empty array singleton that can be assigned without compiler warning. 056 * 057 * @param <L> the left element type. 058 * @param <M> the middle element type. 059 * @param <R> the right element type. 060 * @return the empty array singleton that can be assigned without compiler warning. 061 * @since 3.10 062 */ 063 @SuppressWarnings("unchecked") 064 public static <L, M, R> Triple<L, M, R>[] emptyArray() { 065 return (Triple<L, M, R>[]) EMPTY_ARRAY; 066 } 067 068 /** 069 * Obtains an immutable triple of three objects inferring the generic types. 070 * 071 * <p>This factory allows the triple to be created using inference to 072 * obtain the generic types.</p> 073 * 074 * @param <L> the left element type. 075 * @param <M> the middle element type. 076 * @param <R> the right element type. 077 * @param left the left element, may be null. 078 * @param middle the middle element, may be null. 079 * @param right the right element, may be null. 080 * @return a triple formed from the three parameters, not null. 081 */ 082 public static <L, M, R> Triple<L, M, R> of(final L left, final M middle, final R right) { 083 return ImmutableTriple.of(left, middle, right); 084 } 085 086 /** 087 * Obtains an immutable triple of three non-null objects inferring the generic types. 088 * 089 * <p>This factory allows the triple to be created using inference to 090 * obtain the generic types.</p> 091 * 092 * @param <L> the left element type. 093 * @param <M> the middle element type. 094 * @param <R> the right element type. 095 * @param left the left element, may not be null. 096 * @param middle the middle element, may not be null. 097 * @param right the right element, may not be null. 098 * @return a triple formed from the three parameters, not null. 099 * @throws NullPointerException if any input is null. 100 * @since 3.13.0 101 */ 102 public static <L, M, R> Triple<L, M, R> ofNonNull(final L left, final M middle, final R right) { 103 return ImmutableTriple.ofNonNull(left, middle, right); 104 } 105 106 /** 107 * Constructs a new instance. 108 */ 109 public Triple() { 110 // empty 111 } 112 113 /** 114 * Compares the triple based on the left element, followed by the middle element, 115 * finally the right element. 116 * The types must be {@link Comparable}. 117 * 118 * @param other the other triple, not null. 119 * @return negative if this is less, zero if equal, positive if greater. 120 */ 121 @Override 122 public int compareTo(final Triple<L, M, R> other) { 123 return new CompareToBuilder().append(getLeft(), other.getLeft()) 124 .append(getMiddle(), other.getMiddle()) 125 .append(getRight(), other.getRight()).toComparison(); 126 } 127 128 /** 129 * Compares this triple to another based on the three elements. 130 * 131 * @param obj the object to compare to, null returns false. 132 * @return true if the elements of the triple are equal. 133 */ 134 @Override 135 public boolean equals(final Object obj) { 136 if (obj == this) { 137 return true; 138 } 139 if (obj instanceof Triple<?, ?, ?>) { 140 final Triple<?, ?, ?> other = (Triple<?, ?, ?>) obj; 141 return Objects.equals(getLeft(), other.getLeft()) 142 && Objects.equals(getMiddle(), other.getMiddle()) 143 && Objects.equals(getRight(), other.getRight()); 144 } 145 return false; 146 } 147 148 /** 149 * Gets the left element from this triple. 150 * 151 * @return the left element, may be null. 152 */ 153 public abstract L getLeft(); 154 155 /** 156 * Gets the middle element from this triple. 157 * 158 * @return the middle element, may be null. 159 */ 160 public abstract M getMiddle(); 161 162 /** 163 * Gets the right element from this triple. 164 * 165 * @return the right element, may be null. 166 */ 167 public abstract R getRight(); 168 169 /** 170 * Returns a suitable hash code. 171 * <p> 172 * The hash code is adapted from the definition in {@code Map.Entry}. 173 * </p> 174 * 175 * @return the hash code. 176 */ 177 @Override 178 public int hashCode() { 179 // See Map.Entry API specification 180 return Objects.hashCode(getLeft()) ^ Objects.hashCode(getMiddle()) ^ Objects.hashCode(getRight()); 181 } 182 183 /** 184 * Returns a String representation of this triple using the format {@code (left,middle,right)}. 185 * 186 * @return a string describing this object, not null. 187 */ 188 @Override 189 public String toString() { 190 return "(" + getLeft() + "," + getMiddle() + "," + getRight() + ")"; 191 } 192 193 /** 194 * Formats the receiver using the given format. 195 * 196 * <p>This uses {@link java.util.Formattable} to perform the formatting. Three variables may 197 * be used to embed the left and right elements. Use {@code %1$s} for the left 198 * element, {@code %2$s} for the middle and {@code %3$s} for the right element. 199 * The default format used by {@code toString()} is {@code (%1$s,%2$s,%3$s)}.</p> 200 * 201 * @param format the format string, optionally containing {@code %1$s}, {@code %2$s} and {@code %3$s}, not null. 202 * @return the formatted string, not null. 203 */ 204 public String toString(final String format) { 205 return String.format(format, getLeft(), getMiddle(), getRight()); 206 } 207 208} 209