1a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong/* 2a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved. 3a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * 5a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * This code is free software; you can redistribute it and/or modify it 6a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * under the terms of the GNU General Public License version 2 only, as 7a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * published by the Free Software Foundation. Oracle designates this 8a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * particular file as subject to the "Classpath" exception as provided 9a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * by Oracle in the LICENSE file that accompanied this code. 10a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * 11a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * This code is distributed in the hope that it will be useful, but WITHOUT 12a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * version 2 for more details (a copy is included in the LICENSE file that 15a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * accompanied this code). 16a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * 17a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * You should have received a copy of the GNU General Public License version 18a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * 2 along with this work; if not, write to the Free Software Foundation, 19a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * 21a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * or visit www.oracle.com if you need additional information or have any 23a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * questions. 24a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong */ 25a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kongpackage java.util; 26a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 27a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kongimport java.io.Serializable; 28a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kongimport java.util.function.BinaryOperator; 29a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kongimport java.util.function.Function; 30a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kongimport java.util.function.ToDoubleFunction; 31a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kongimport java.util.function.ToIntFunction; 32a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kongimport java.util.function.ToLongFunction; 33a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 34a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong/** 35a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * Package private supporting class for {@link Comparator}. 36a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong */ 37a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kongclass Comparators { 38a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong private Comparators() { 39a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong throw new AssertionError("no instances"); 40a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 41a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 42a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong /** 43a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * Compares {@link Comparable} objects in natural order. 44a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * 45a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * @see Comparable 46a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong */ 47a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong enum NaturalOrderComparator implements Comparator<Comparable<Object>> { 48a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong INSTANCE; 49a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 50a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong @Override 51a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong public int compare(Comparable<Object> c1, Comparable<Object> c2) { 52a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong return c1.compareTo(c2); 53a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 54a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 55a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong @Override 56a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong public Comparator<Comparable<Object>> reversed() { 57a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong return Comparator.reverseOrder(); 58a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 59a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 60a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 61a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong /** 62a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong * Null-friendly comparators 63a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong */ 64a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong final static class NullComparator<T> implements Comparator<T>, Serializable { 65a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong private static final long serialVersionUID = -7569533591570686392L; 66a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong private final boolean nullFirst; 67a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong // if null, non-null Ts are considered equal 68a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong private final Comparator<T> real; 69a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 70a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong @SuppressWarnings("unchecked") 71a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong NullComparator(boolean nullFirst, Comparator<? super T> real) { 72a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong this.nullFirst = nullFirst; 73a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong this.real = (Comparator<T>) real; 74a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 75a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 76a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong @Override 77a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong public int compare(T a, T b) { 78a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong if (a == null) { 79a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong return (b == null) ? 0 : (nullFirst ? -1 : 1); 80a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } else if (b == null) { 81a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong return nullFirst ? 1: -1; 82a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } else { 83a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong return (real == null) ? 0 : real.compare(a, b); 84a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 85a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 86a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 87a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong @Override 88a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong public Comparator<T> thenComparing(Comparator<? super T> other) { 89a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong Objects.requireNonNull(other); 90a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong return new NullComparator<>(nullFirst, real == null ? other : real.thenComparing(other)); 91a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 92a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong 93a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong @Override 94a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong public Comparator<T> reversed() { 95a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong return new NullComparator<>(!nullFirst, real == null ? null : real.reversed()); 96a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 97a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong } 98a8da445cdc91374ed0e105686feefd7e8ed79dc1Yi Kong} 99