Showing the changes to java/pkg/sun/applet/AppletEventMulticaster.java (1 of 18352 files). Show all
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| 1 | +/* | |
| 2 | + * Copyright (c) 1997, 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 sun.applet; | |
| 27 | + | |
| 28 | +import java.util.EventListener; | |
| 29 | +import java.io.Serializable; | |
| 30 | +import java.io.ObjectOutputStream; | |
| 31 | +import java.io.IOException; | |
| 32 | + | |
| 33 | +/** | |
| 34 | + * AppletEventMulticaster class. This class manages an immutable | |
| 35 | + * structure consisting of a chain of AppletListeners and is | |
| 36 | + * responsible for dispatching events to them. | |
| 37 | + * | |
| 38 | + * @author Sunita Mani | |
| 39 | + */ | |
| 40 | +public class AppletEventMulticaster implements AppletListener { | |
| 41 | + | |
| 42 | + private final AppletListener a, b; | |
| 43 | + | |
| 44 | + public AppletEventMulticaster(AppletListener a, AppletListener b) { | |
| 45 | + this.a = a; this.b = b; | |
| 46 | + } | |
| 47 | + | |
| 48 | + public void appletStateChanged(AppletEvent e) { | |
| 49 | + a.appletStateChanged(e); | |
| 50 | + b.appletStateChanged(e); | |
| 51 | + } | |
| 52 | + | |
| 53 | + /** | |
| 54 | + * Adds Applet-listener-a with Applet-listener-b and | |
| 55 | + * returns the resulting multicast listener. | |
| 56 | + * @param a Applet-listener-a | |
| 57 | + * @param b Applet-listener-b | |
| 58 | + */ | |
| 59 | + public static AppletListener add(AppletListener a, AppletListener b) { | |
| 60 | + return addInternal(a, b); | |
| 61 | + } | |
| 62 | + | |
| 63 | + /** | |
| 64 | + * Removes the old Applet-listener from Applet-listener-l and | |
| 65 | + * returns the resulting multicast listener. | |
| 66 | + * @param l Applet-listener-l | |
| 67 | + * @param oldl the Applet-listener being removed | |
| 68 | + */ | |
| 69 | + public static AppletListener remove(AppletListener l, AppletListener oldl) { | |
| 70 | + return removeInternal(l, oldl); | |
| 71 | + } | |
| 72 | + | |
| 73 | + /** | |
| 74 | + * Returns the resulting multicast listener from adding listener-a | |
| 75 | + * and listener-b together. | |
| 76 | + * If listener-a is null, it returns listener-b; | |
| 77 | + * If listener-b is null, it returns listener-a | |
| 78 | + * If neither are null, then it creates and returns | |
| 79 | + * a new AppletEventMulticaster instance which chains a with b. | |
| 80 | + * @param a event listener-a | |
| 81 | + * @param b event listener-b | |
| 82 | + */ | |
| 83 | + private static AppletListener addInternal(AppletListener a, AppletListener b) { | |
| 84 | + if (a == null) return b; | |
| 85 | + if (b == null) return a; | |
| 86 | + return new AppletEventMulticaster(a, b); | |
| 87 | + } | |
| 88 | + | |
| 89 | + | |
| 90 | + /** | |
| 91 | + * Removes a listener from this multicaster and returns the | |
| 92 | + * resulting multicast listener. | |
| 93 | + * @param oldl the listener to be removed | |
| 94 | + */ | |
| 95 | + protected AppletListener remove(AppletListener oldl) { | |
| 96 | + if (oldl == a) return b; | |
| 97 | + if (oldl == b) return a; | |
| 98 | + AppletListener a2 = removeInternal(a, oldl); | |
| 99 | + AppletListener b2 = removeInternal(b, oldl); | |
| 100 | + if (a2 == a && b2 == b) { | |
| 101 | + return this; // it's not here | |
| 102 | + } | |
| 103 | + return addInternal(a2, b2); | |
| 104 | + } | |
| 105 | + | |
| 106 | + | |
| 107 | + /** | |
| 108 | + * Returns the resulting multicast listener after removing the | |
| 109 | + * old listener from listener-l. | |
| 110 | + * If listener-l equals the old listener OR listener-l is null, | |
| 111 | + * returns null. | |
| 112 | + * Else if listener-l is an instance of AppletEventMulticaster | |
| 113 | + * then it removes the old listener from it. | |
| 114 | + * Else, returns listener l. | |
| 115 | + * @param l the listener being removed from | |
| 116 | + * @param oldl the listener being removed | |
| 117 | + */ | |
| 118 | + private static AppletListener removeInternal(AppletListener l, AppletListener oldl) { | |
| 119 | + if (l == oldl || l == null) { | |
| 120 | + return null; | |
| 121 | + } else if (l instanceof AppletEventMulticaster) { | |
| 122 | + return ((AppletEventMulticaster)l).remove(oldl); | |
| 123 | + } else { | |
| 124 | + return l; // it's not here | |
| 125 | + } | |
| 126 | + } | |
| 127 | +} | |