1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.commons.lang3.compare; 19 20 import java.io.Serializable; 21 import java.util.Comparator; 22 23 /** 24 * Compares Object's {@link Object#toString()} values. 25 * 26 * This class is stateless. 27 * 28 * @since 3.10 29 */ 30 public final class ObjectToStringComparator implements Comparator<Object>, Serializable { 31 32 /** 33 * Singleton instance. 34 * 35 * This class is stateless. 36 */ 37 public static final ObjectToStringComparator INSTANCE = new ObjectToStringComparator(); 38 39 /** 40 * For {@link Serializable}. 41 */ 42 private static final long serialVersionUID = 1L; 43 44 @Override compare(final Object o1, final Object o2)45 public int compare(final Object o1, final Object o2) { 46 if (o1 == null && o2 == null) { 47 return 0; 48 } 49 if (o1 == null) { 50 return 1; 51 } 52 if (o2 == null) { 53 return -1; 54 } 55 final String string1 = o1.toString(); 56 final String string2 = o2.toString(); 57 // No guarantee that toString() returns a non-null value, despite what Spotbugs thinks. 58 if (string1 == null && string2 == null) { 59 return 0; 60 } 61 if (string1 == null) { 62 return 1; 63 } 64 if (string2 == null) { 65 return -1; 66 } 67 return string1.compareTo(string2); 68 } 69 } 70