1 /* 2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package com.sun.javafx.scene.control; 27 28 import javafx.beans.value.ChangeListener; 29 import javafx.beans.value.ObservableValue; 30 import javafx.beans.value.WeakChangeListener; 31 32 import java.util.ArrayList; 33 import java.util.Collections; 34 import java.util.HashMap; 35 import java.util.List; 36 import java.util.Map; 37 import java.util.function.Consumer; 38 39 public final class LambdaMultiplePropertyChangeListenerHandler { 40 41 private final Map<ObservableValue<?>, List<Consumer<ObservableValue<?>>>> propertyReferenceMap; 42 private final ChangeListener<Object> propertyChangedListener; 43 private final WeakChangeListener<Object> weakPropertyChangedListener; 44 45 public LambdaMultiplePropertyChangeListenerHandler() { 46 this.propertyReferenceMap = new HashMap<>(); 47 this.propertyChangedListener = (observable, oldValue, newValue) -> { 48 List<Consumer<ObservableValue<?>>> callbacks = propertyReferenceMap.getOrDefault(observable, Collections.emptyList()); 49 for (Consumer<ObservableValue<?>> callback : callbacks) { 50 callback.accept(observable); 51 } 52 }; 53 this.weakPropertyChangedListener = new WeakChangeListener<>(propertyChangedListener); 54 } 55 56 /** 57 * Subclasses can invoke this method to register that we want to listen to 58 * property change events for the given property. 59 * 60 * @param property 61 */ 62 public final void registerChangeListener(ObservableValue<?> property, Consumer<ObservableValue<?>> consumer) { 63 if (consumer == null) return; 64 List<Consumer<ObservableValue<?>>> callbacks = propertyReferenceMap.computeIfAbsent(property, p -> new ArrayList<>()); 65 callbacks.add(consumer); 66 67 // we only add a listener if the callbacks list contains only one element 68 // (that is, we've added a consumer to this specific property for the first 69 // time). 70 if (callbacks.size() == 1) { 71 property.addListener(weakPropertyChangedListener); 72 } 73 } 74 75 // need to be careful here - removing all listeners on the specific property! 76 public final void unregisterChangeListener(ObservableValue<?> property) { 77 if (propertyReferenceMap.containsKey(property)) { 78 propertyReferenceMap.remove(property); 79 property.removeListener(weakPropertyChangedListener); 80 } 81 } 82 83 public void dispose() { 84 // unhook listeners 85 for (ObservableValue<?> value : propertyReferenceMap.keySet()) { 86 value.removeListener(weakPropertyChangedListener); 87 } 88 propertyReferenceMap.clear(); 89 } 90 }