001/* 002 * Copyright 2002-2013 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.expression; 018 019/** 020 * Instances of a type comparator should be able to compare pairs of objects for equality. 021 * The specification of the return value is the same as for {@link java.lang.Comparable}. 022 * 023 * @author Andy Clement 024 * @since 3.0 025 * @see java.lang.Comparable 026 */ 027public interface TypeComparator { 028 029 /** 030 * Return {@code true} if the comparator can compare these two objects. 031 * @param firstObject the first object 032 * @param secondObject the second object 033 * @return {@code true} if the comparator can compare these objects 034 */ 035 boolean canCompare(Object firstObject, Object secondObject); 036 037 /** 038 * Compare two given objects. 039 * @param firstObject the first object 040 * @param secondObject the second object 041 * @return 0 if they are equal, <0 if the first is smaller than the second, 042 * or >0 if the first is larger than the second 043 * @throws EvaluationException if a problem occurs during comparison 044 * (or if they are not comparable in the first place) 045 */ 046 int compare(Object firstObject, Object secondObject) throws EvaluationException; 047 048}