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 * http://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.wicket.model; 018 019import org.apache.wicket.Component; 020import org.apache.wicket.util.io.IClusterable; 021 022/** 023 * Implementations of this interface compare model object. The component is given so that a 024 * developer can choose what the previous object is The default implementation for form components 025 * is just component.getModelObject(); But developers can choose to keep the last rendered value for 026 * that component and compare this value with the newObject. So that it doesn't overwrite values for 027 * an object that was changed by another session if the current session didn't touch that specific 028 * value. 029 * 030 * @author jcompagner 031 * @author Jonathan Locke 032 * 033 */ 034@FunctionalInterface 035public interface IModelComparator extends IClusterable 036{ 037 /** 038 * A model comparator that always returns false 039 */ 040 IModelComparator ALWAYS_FALSE = (IModelComparator) (component, newObject) -> false; 041 042 /** 043 * @param component 044 * The component which received the new object 045 * @param newObject 046 * The newObject 047 * @return True if the previous components object is the same as the newObject. 048 */ 049 boolean compare(Component component, Object newObject); 050}