Java tutorial
/* * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.awt.event; import java.awt.Window; import java.lang.annotation.Native; import sun.awt.AppContext; import sun.awt.SunToolkit; /** * A low-level event that indicates that a window has changed its status. This * low-level event is generated by a Window object when it is opened, closed, * activated, deactivated, iconified, or deiconified, or when focus is * transferred into or out of the Window. * <P> * The event is passed to every {@code WindowListener} * or {@code WindowAdapter} object which registered to receive such * events using the window's {@code addWindowListener} method. * ({@code WindowAdapter} objects implement the * {@code WindowListener} interface.) Each such listener object * gets this {@code WindowEvent} when the event occurs. * <p> * An unspecified behavior will be caused if the {@code id} parameter * of any particular {@code WindowEvent} instance is not * in the range from {@code WINDOW_FIRST} to {@code WINDOW_LAST}. * * @author Carl Quinn * @author Amy Fowler * * @see WindowAdapter * @see WindowListener * @see <a href="https://docs.oracle.com/javase/tutorial/uiswing/events/windowlistener.html">Tutorial: Writing a Window Listener</a> * * @since 1.1 */ public class WindowEvent extends ComponentEvent { /** * The first number in the range of ids used for window events. */ public static final int WINDOW_FIRST = 200; /** * The window opened event. This event is delivered only * the first time a window is made visible. */ @Native public static final int WINDOW_OPENED = WINDOW_FIRST; // 200 /** * The "window is closing" event. This event is delivered when * the user attempts to close the window from the window's system menu. * If the program does not explicitly hide or dispose the window * while processing this event, the window close operation will be * cancelled. */ @Native public static final int WINDOW_CLOSING = 1 + WINDOW_FIRST; //Event.WINDOW_DESTROY /** * The window closed event. This event is delivered after the displayable * window has been closed as the result of a call to dispose. * @see java.awt.Component#isDisplayable * @see Window#dispose */ @Native public static final int WINDOW_CLOSED = 2 + WINDOW_FIRST; /** * The window iconified event. This event is delivered when * the window has been changed from a normal to a minimized state. * For many platforms, a minimized window is displayed as * the icon specified in the window's iconImage property. * @see java.awt.Frame#setIconImage */ @Native public static final int WINDOW_ICONIFIED = 3 + WINDOW_FIRST; //Event.WINDOW_ICONIFY /** * The window deiconified event type. This event is delivered when * the window has been changed from a minimized to a normal state. */ @Native public static final int WINDOW_DEICONIFIED = 4 + WINDOW_FIRST; //Event.WINDOW_DEICONIFY /** * The window-activated event type. This event is delivered when the Window * becomes the active Window. Only a Frame or a Dialog can be the active * Window. The native windowing system may denote the active Window or its * children with special decorations, such as a highlighted title bar. The * active Window is always either the focused Window, or the first Frame or * Dialog that is an owner of the focused Window. */ @Native public static final int WINDOW_ACTIVATED = 5 + WINDOW_FIRST; /** * The window-deactivated event type. This event is delivered when the * Window is no longer the active Window. Only a Frame or a Dialog can be * the active Window. The native windowing system may denote the active * Window or its children with special decorations, such as a highlighted * title bar. The active Window is always either the focused Window, or the * first Frame or Dialog that is an owner of the focused Window. */ @Native public static final int WINDOW_DEACTIVATED = 6 + WINDOW_FIRST; /** * The window-gained-focus event type. This event is delivered when the * Window becomes the focused Window, which means that the Window, or one * of its subcomponents, will receive keyboard events. */ @Native public static final int WINDOW_GAINED_FOCUS = 7 + WINDOW_FIRST; /** * The window-lost-focus event type. This event is delivered when a Window * is no longer the focused Window, which means keyboard events will no * longer be delivered to the Window or any of its subcomponents. */ @Native public static final int WINDOW_LOST_FOCUS = 8 + WINDOW_FIRST; /** * The window-state-changed event type. This event is delivered * when a Window's state is changed by virtue of it being * iconified, maximized etc. * @since 1.4 */ @Native public static final int WINDOW_STATE_CHANGED = 9 + WINDOW_FIRST; /** * The last number in the range of ids used for window events. */ public static final int WINDOW_LAST = WINDOW_STATE_CHANGED; /** * The other Window involved in this focus or activation change. For a * WINDOW_ACTIVATED or WINDOW_GAINED_FOCUS event, this is the Window that * lost activation or focus. For a WINDOW_DEACTIVATED or WINDOW_LOST_FOCUS * event, this is the Window that gained activation or focus. For any other * type of WindowEvent, or if the focus or activation change occurs with a * native application, a Java application in a different VM, or with no * other Window, null is returned. * * @see #getOppositeWindow * @since 1.4 */ transient Window opposite; /** * TBS */ int oldState; int newState; /* * JDK 1.1 serialVersionUID */ private static final long serialVersionUID = -1567959133147912127L; /** * Constructs a {@code WindowEvent} object. * <p>This method throws an * {@code IllegalArgumentException} if {@code source} * is {@code null}. * * @param source The {@code Window} object * that originated the event * @param id An integer indicating the type of event. * For information on allowable values, see * the class description for {@link WindowEvent} * @param opposite The other window involved in the focus or activation * change, or {@code null} * @param oldState Previous state of the window for window state change event. * See {@code #getOldState()} for allowable values * @param newState New state of the window for window state change event. * See {@code #getNewState()} for allowable values * @throws IllegalArgumentException if {@code source} is null * @see #getWindow() * @see #getID() * @see #getOppositeWindow() * @see #getOldState() * @see #getNewState() * @since 1.4 */ public WindowEvent(Window source, int id, Window opposite, int oldState, int newState) { super(source, id); this.opposite = opposite; this.oldState = oldState; this.newState = newState; } /** * Constructs a {@code WindowEvent} object with the * specified opposite {@code Window}. The opposite * {@code Window} is the other {@code Window} * involved in this focus or activation change. * For a {@code WINDOW_ACTIVATED} or * {@code WINDOW_GAINED_FOCUS} event, this is the * {@code Window} that lost activation or focus. * For a {@code WINDOW_DEACTIVATED} or * {@code WINDOW_LOST_FOCUS} event, this is the * {@code Window} that gained activation or focus. * If this focus change occurs with a native application, with a * Java application in a different VM, or with no other * {@code Window}, then the opposite Window is {@code null}. * <p>This method throws an * {@code IllegalArgumentException} if {@code source} * is {@code null}. * * @param source The {@code Window} object that * originated the event * @param id An integer indicating the type of event. * For information on allowable values, see * the class description for {@link WindowEvent}. * It is expected that this constructor will not * be used for other then * {@code WINDOW_ACTIVATED},{@code WINDOW_DEACTIVATED}, * {@code WINDOW_GAINED_FOCUS}, or {@code WINDOW_LOST_FOCUS}. * {@code WindowEvent} types, * because the opposite {@code Window} of other event types * will always be {@code null}. * @param opposite The other {@code Window} involved in the * focus or activation change, or {@code null} * @throws IllegalArgumentException if {@code source} is null * @see #getWindow() * @see #getID() * @see #getOppositeWindow() * @since 1.4 */ public WindowEvent(Window source, int id, Window opposite) { this(source, id, opposite, 0, 0); } /** * Constructs a {@code WindowEvent} object with the specified * previous and new window states. * <p>This method throws an * {@code IllegalArgumentException} if {@code source} * is {@code null}. * * @param source The {@code Window} object * that originated the event * @param id An integer indicating the type of event. * For information on allowable values, see * the class description for {@link WindowEvent}. * It is expected that this constructor will not * be used for other then * {@code WINDOW_STATE_CHANGED} * {@code WindowEvent} * types, because the previous and new window * states are meaningless for other event types. * @param oldState An integer representing the previous window state. * See {@code #getOldState()} for allowable values * @param newState An integer representing the new window state. * See {@code #getNewState()} for allowable values * @throws IllegalArgumentException if {@code source} is null * @see #getWindow() * @see #getID() * @see #getOldState() * @see #getNewState() * @since 1.4 */ public WindowEvent(Window source, int id, int oldState, int newState) { this(source, id, null, oldState, newState); } /** * Constructs a {@code WindowEvent} object. * <p>This method throws an * {@code IllegalArgumentException} if {@code source} * is {@code null}. * * @param source The {@code Window} object that originated the event * @param id An integer indicating the type of event. * For information on allowable values, see * the class description for {@link WindowEvent}. * @throws IllegalArgumentException if {@code source} is null * @see #getWindow() * @see #getID() */ public WindowEvent(Window source, int id) { this(source, id, null, 0, 0); } /** * Returns the originator of the event. * * @return the Window object that originated the event */ public Window getWindow() { return (source instanceof Window) ? (Window) source : null; } /** * Returns the other Window involved in this focus or activation change. * For a WINDOW_ACTIVATED or WINDOW_GAINED_FOCUS event, this is the Window * that lost activation or focus. For a WINDOW_DEACTIVATED or * WINDOW_LOST_FOCUS event, this is the Window that gained activation or * focus. For any other type of WindowEvent, or if the focus or activation * change occurs with a native application, with a Java application in a * different VM or context, or with no other Window, null is returned. * * @return the other Window involved in the focus or activation change, or * null * @since 1.4 */ public Window getOppositeWindow() { if (opposite == null) { return null; } return (SunToolkit.targetToAppContext(opposite) == AppContext.getAppContext()) ? opposite : null; } /** * For {@code WINDOW_STATE_CHANGED} events returns the * previous state of the window. The state is * represented as a bitwise mask. * <ul> * <li>{@code NORMAL} * <br>Indicates that no state bits are set. * <li>{@code ICONIFIED} * <li>{@code MAXIMIZED_HORIZ} * <li>{@code MAXIMIZED_VERT} * <li>{@code MAXIMIZED_BOTH} * <br>Concatenates {@code MAXIMIZED_HORIZ} * and {@code MAXIMIZED_VERT}. * </ul> * * @return a bitwise mask of the previous window state * @see java.awt.Frame#getExtendedState() * @since 1.4 */ public int getOldState() { return oldState; } /** * For {@code WINDOW_STATE_CHANGED} events returns the * new state of the window. The state is * represented as a bitwise mask. * <ul> * <li>{@code NORMAL} * <br>Indicates that no state bits are set. * <li>{@code ICONIFIED} * <li>{@code MAXIMIZED_HORIZ} * <li>{@code MAXIMIZED_VERT} * <li>{@code MAXIMIZED_BOTH} * <br>Concatenates {@code MAXIMIZED_HORIZ} * and {@code MAXIMIZED_VERT}. * </ul> * * @return a bitwise mask of the new window state * @see java.awt.Frame#getExtendedState() * @since 1.4 */ public int getNewState() { return newState; } /** * Returns a parameter string identifying this event. * This method is useful for event-logging and for debugging. * * @return a string identifying the event and its attributes */ public String paramString() { String typeStr; switch (id) { case WINDOW_OPENED: typeStr = "WINDOW_OPENED"; break; case WINDOW_CLOSING: typeStr = "WINDOW_CLOSING"; break; case WINDOW_CLOSED: typeStr = "WINDOW_CLOSED"; break; case WINDOW_ICONIFIED: typeStr = "WINDOW_ICONIFIED"; break; case WINDOW_DEICONIFIED: typeStr = "WINDOW_DEICONIFIED"; break; case WINDOW_ACTIVATED: typeStr = "WINDOW_ACTIVATED"; break; case WINDOW_DEACTIVATED: typeStr = "WINDOW_DEACTIVATED"; break; case WINDOW_GAINED_FOCUS: typeStr = "WINDOW_GAINED_FOCUS"; break; case WINDOW_LOST_FOCUS: typeStr = "WINDOW_LOST_FOCUS"; break; case WINDOW_STATE_CHANGED: typeStr = "WINDOW_STATE_CHANGED"; break; default: typeStr = "unknown type"; } typeStr += ",opposite=" + getOppositeWindow() + ",oldState=" + oldState + ",newState=" + newState; return typeStr; } }