java.awt.Event.java Source code

Java tutorial

Introduction

Here is the source code for java.awt.Event.java

Source

/*
 * Copyright (c) 1995, 2018, 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;

import java.awt.event.KeyEvent;

/**
 * <b>NOTE:</b> The {@code Event} class is obsolete and is
 * available only for backwards compatibility.  It has been replaced
 * by the {@code AWTEvent} class and its subclasses.
 * <p>
 * {@code Event} is a platform-independent class that
 * encapsulates events from the platform's Graphical User
 * Interface in the Java&nbsp;1.0 event model. In Java&nbsp;1.1
 * and later versions, the {@code Event} class is maintained
 * only for backwards compatibility. The information in this
 * class description is provided to assist programmers in
 * converting Java&nbsp;1.0 programs to the new event model.
 * <p>
 * In the Java&nbsp;1.0 event model, an event contains an
 * {@link Event#id} field
 * that indicates what type of event it is and which other
 * {@code Event} variables are relevant for the event.
 * <p>
 * For keyboard events, {@link Event#key}
 * contains a value indicating which key was activated, and
 * {@link Event#modifiers} contains the
 * modifiers for that event.  For the KEY_PRESS and KEY_RELEASE
 * event ids, the value of {@code key} is the unicode
 * character code for the key. For KEY_ACTION and
 * KEY_ACTION_RELEASE, the value of {@code key} is
 * one of the defined action-key identifiers in the
 * {@code Event} class ({@code PGUP},
 * {@code PGDN}, {@code F1}, {@code F2}, etc).
 *
 * @deprecated It is recommended that {@code AWTEvent} and its subclasses be
 *             used instead
 * @author     Sami Shaio
 * @since      1.0
 */
@Deprecated(since = "9")
public class Event implements java.io.Serializable {
    private transient long data;

    /* Modifier constants */

    /**
     * This flag indicates that the Shift key was down when the event
     * occurred.
     */
    public static final int SHIFT_MASK = 1 << 0;

    /**
     * This flag indicates that the Control key was down when the event
     * occurred.
     */
    public static final int CTRL_MASK = 1 << 1;

    /**
     * This flag indicates that the Meta key was down when the event
     * occurred. For mouse events, this flag indicates that the right
     * button was pressed or released.
     */
    public static final int META_MASK = 1 << 2;

    /**
     * This flag indicates that the Alt key was down when
     * the event occurred. For mouse events, this flag indicates that the
     * middle mouse button was pressed or released.
     */
    public static final int ALT_MASK = 1 << 3;

    /* Action keys */

    /**
     * The Home key, a non-ASCII action key.
     */
    public static final int HOME = 1000;

    /**
     * The End key, a non-ASCII action key.
     */
    public static final int END = 1001;

    /**
     * The Page Up key, a non-ASCII action key.
     */
    public static final int PGUP = 1002;

    /**
     * The Page Down key, a non-ASCII action key.
     */
    public static final int PGDN = 1003;

    /**
     * The Up Arrow key, a non-ASCII action key.
     */
    public static final int UP = 1004;

    /**
     * The Down Arrow key, a non-ASCII action key.
     */
    public static final int DOWN = 1005;

    /**
     * The Left Arrow key, a non-ASCII action key.
     */
    public static final int LEFT = 1006;

    /**
     * The Right Arrow key, a non-ASCII action key.
     */
    public static final int RIGHT = 1007;

    /**
     * The F1 function key, a non-ASCII action key.
     */
    public static final int F1 = 1008;

    /**
     * The F2 function key, a non-ASCII action key.
     */
    public static final int F2 = 1009;

    /**
     * The F3 function key, a non-ASCII action key.
     */
    public static final int F3 = 1010;

    /**
     * The F4 function key, a non-ASCII action key.
     */
    public static final int F4 = 1011;

    /**
     * The F5 function key, a non-ASCII action key.
     */
    public static final int F5 = 1012;

    /**
     * The F6 function key, a non-ASCII action key.
     */
    public static final int F6 = 1013;

    /**
     * The F7 function key, a non-ASCII action key.
     */
    public static final int F7 = 1014;

    /**
     * The F8 function key, a non-ASCII action key.
     */
    public static final int F8 = 1015;

    /**
     * The F9 function key, a non-ASCII action key.
     */
    public static final int F9 = 1016;

    /**
     * The F10 function key, a non-ASCII action key.
     */
    public static final int F10 = 1017;

    /**
     * The F11 function key, a non-ASCII action key.
     */
    public static final int F11 = 1018;

    /**
     * The F12 function key, a non-ASCII action key.
     */
    public static final int F12 = 1019;

    /**
     * The Print Screen key, a non-ASCII action key.
     */
    public static final int PRINT_SCREEN = 1020;

    /**
     * The Scroll Lock key, a non-ASCII action key.
     */
    public static final int SCROLL_LOCK = 1021;

    /**
     * The Caps Lock key, a non-ASCII action key.
     */
    public static final int CAPS_LOCK = 1022;

    /**
     * The Num Lock key, a non-ASCII action key.
     */
    public static final int NUM_LOCK = 1023;

    /**
     * The Pause key, a non-ASCII action key.
     */
    public static final int PAUSE = 1024;

    /**
     * The Insert key, a non-ASCII action key.
     */
    public static final int INSERT = 1025;

    /* Non-action keys */

    /**
     * The Enter key.
     */
    public static final int ENTER = '\n';

    /**
     * The BackSpace key.
     */
    public static final int BACK_SPACE = '\b';

    /**
     * The Tab key.
     */
    public static final int TAB = '\t';

    /**
     * The Escape key.
     */
    public static final int ESCAPE = 27;

    /**
     * The Delete key.
     */
    public static final int DELETE = 127;

    /* Base for all window events. */
    private static final int WINDOW_EVENT = 200;

    /**
     * The user has asked the window manager to kill the window.
     */
    public static final int WINDOW_DESTROY = 1 + WINDOW_EVENT;

    /**
     * The user has asked the window manager to expose the window.
     */
    public static final int WINDOW_EXPOSE = 2 + WINDOW_EVENT;

    /**
     * The user has asked the window manager to iconify the window.
     */
    public static final int WINDOW_ICONIFY = 3 + WINDOW_EVENT;

    /**
     * The user has asked the window manager to de-iconify the window.
     */
    public static final int WINDOW_DEICONIFY = 4 + WINDOW_EVENT;

    /**
     * The user has asked the window manager to move the window.
     */
    public static final int WINDOW_MOVED = 5 + WINDOW_EVENT;

    /* Base for all keyboard events. */
    private static final int KEY_EVENT = 400;

    /**
     * The user has pressed a normal key.
     */
    public static final int KEY_PRESS = 1 + KEY_EVENT;

    /**
     * The user has released a normal key.
     */
    public static final int KEY_RELEASE = 2 + KEY_EVENT;

    /**
     * The user has pressed a non-ASCII <em>action</em> key.
     * The {@code key} field contains a value that indicates
     * that the event occurred on one of the action keys, which
     * comprise the 12 function keys, the arrow (cursor) keys,
     * Page Up, Page Down, Home, End, Print Screen, Scroll Lock,
     * Caps Lock, Num Lock, Pause, and Insert.
     */
    public static final int KEY_ACTION = 3 + KEY_EVENT;

    /**
     * The user has released a non-ASCII <em>action</em> key.
     * The {@code key} field contains a value that indicates
     * that the event occurred on one of the action keys, which
     * comprise the 12 function keys, the arrow (cursor) keys,
     * Page Up, Page Down, Home, End, Print Screen, Scroll Lock,
     * Caps Lock, Num Lock, Pause, and Insert.
     */
    public static final int KEY_ACTION_RELEASE = 4 + KEY_EVENT;

    /* Base for all mouse events. */
    private static final int MOUSE_EVENT = 500;

    /**
     * The user has pressed the mouse button. The {@code ALT_MASK}
     * flag indicates that the middle button has been pressed.
     * The {@code META_MASK} flag indicates that the
     * right button has been pressed.
     * @see     java.awt.Event#ALT_MASK
     * @see     java.awt.Event#META_MASK
     */
    public static final int MOUSE_DOWN = 1 + MOUSE_EVENT;

    /**
     * The user has released the mouse button. The {@code ALT_MASK}
     * flag indicates that the middle button has been released.
     * The {@code META_MASK} flag indicates that the
     * right button has been released.
     * @see     java.awt.Event#ALT_MASK
     * @see     java.awt.Event#META_MASK
     */
    public static final int MOUSE_UP = 2 + MOUSE_EVENT;

    /**
     * The mouse has moved with no button pressed.
     */
    public static final int MOUSE_MOVE = 3 + MOUSE_EVENT;

    /**
     * The mouse has entered a component.
     */
    public static final int MOUSE_ENTER = 4 + MOUSE_EVENT;

    /**
     * The mouse has exited a component.
     */
    public static final int MOUSE_EXIT = 5 + MOUSE_EVENT;

    /**
     * The user has moved the mouse with a button pressed. The
     * {@code ALT_MASK} flag indicates that the middle
     * button is being pressed. The {@code META_MASK} flag indicates
     * that the right button is being pressed.
     * @see     java.awt.Event#ALT_MASK
     * @see     java.awt.Event#META_MASK
     */
    public static final int MOUSE_DRAG = 6 + MOUSE_EVENT;

    /* Scrolling events */
    private static final int SCROLL_EVENT = 600;

    /**
     * The user has activated the <em>line up</em>
     * area of a scroll bar.
     */
    public static final int SCROLL_LINE_UP = 1 + SCROLL_EVENT;

    /**
     * The user has activated the <em>line down</em>
     * area of a scroll bar.
     */
    public static final int SCROLL_LINE_DOWN = 2 + SCROLL_EVENT;

    /**
     * The user has activated the <em>page up</em>
     * area of a scroll bar.
     */
    public static final int SCROLL_PAGE_UP = 3 + SCROLL_EVENT;

    /**
     * The user has activated the <em>page down</em>
     * area of a scroll bar.
     */
    public static final int SCROLL_PAGE_DOWN = 4 + SCROLL_EVENT;

    /**
     * The user has moved the bubble (thumb) in a scroll bar,
     * moving to an "absolute" position, rather than to
     * an offset from the last position.
     */
    public static final int SCROLL_ABSOLUTE = 5 + SCROLL_EVENT;

    /**
     * The scroll begin event.
     */
    public static final int SCROLL_BEGIN = 6 + SCROLL_EVENT;

    /**
     * The scroll end event.
     */
    public static final int SCROLL_END = 7 + SCROLL_EVENT;

    /* List Events */
    private static final int LIST_EVENT = 700;

    /**
     * An item in a list has been selected.
     */
    public static final int LIST_SELECT = 1 + LIST_EVENT;

    /**
     * An item in a list has been deselected.
     */
    public static final int LIST_DESELECT = 2 + LIST_EVENT;

    /* Misc Event */
    private static final int MISC_EVENT = 1000;

    /**
     * This event indicates that the user wants some action to occur.
     */
    public static final int ACTION_EVENT = 1 + MISC_EVENT;

    /**
     * A file loading event.
     */
    public static final int LOAD_FILE = 2 + MISC_EVENT;

    /**
     * A file saving event.
     */
    public static final int SAVE_FILE = 3 + MISC_EVENT;

    /**
     * A component gained the focus.
     */
    public static final int GOT_FOCUS = 4 + MISC_EVENT;

    /**
     * A component lost the focus.
     */
    public static final int LOST_FOCUS = 5 + MISC_EVENT;

    /**
     * The target component. This indicates the component over which the
     * event occurred or with which the event is associated.
     * This object has been replaced by AWTEvent.getSource()
     *
     * @serial
     * @see java.awt.AWTEvent#getSource()
     */
    public Object target;

    /**
     * The time stamp.
     * Replaced by InputEvent.getWhen().
     *
     * @serial
     * @see java.awt.event.InputEvent#getWhen()
     */
    public long when;

    /**
     * Indicates which type of event the event is, and which
     * other {@code Event} variables are relevant for the event.
     * This has been replaced by AWTEvent.getID()
     *
     * @serial
     * @see java.awt.AWTEvent#getID()
     */
    public int id;

    /**
     * The <i>x</i> coordinate of the event.
     * Replaced by MouseEvent.getX()
     *
     * @serial
     * @see java.awt.event.MouseEvent#getX()
     */
    public int x;

    /**
     * The <i>y</i> coordinate of the event.
     * Replaced by MouseEvent.getY()
     *
     * @serial
     * @see java.awt.event.MouseEvent#getY()
     */
    public int y;

    /**
     * The key code of the key that was pressed in a keyboard event.
     * This has been replaced by KeyEvent.getKeyCode()
     *
     * @serial
     * @see java.awt.event.KeyEvent#getKeyCode()
     */
    public int key;

    /**
     * The key character that was pressed in a keyboard event.
     */
    //    public char keyChar;

    /**
     * The state of the modifier keys.
     * This is replaced with InputEvent.getModifiers()
     * In java 1.1 MouseEvent and KeyEvent are subclasses
     * of InputEvent.
     *
     * @serial
     * @see java.awt.event.InputEvent#getModifiers()
     */
    public int modifiers;

    /**
     * For {@code MOUSE_DOWN} events, this field indicates the
     * number of consecutive clicks. For other events, its value is
     * {@code 0}.
     * This field has been replaced by MouseEvent.getClickCount().
     *
     * @serial
     * @see java.awt.event.MouseEvent#getClickCount()
     */
    public int clickCount;

    /**
     * An arbitrary argument of the event. The value of this field
     * depends on the type of event.
     * {@code arg} has been replaced by event specific property.
     *
     * @serial
     */
    public Object arg;

    /**
     * The next event. This field is set when putting events into a
     * linked list.
     * This has been replaced by EventQueue.
     *
     * @serial
     * @see java.awt.EventQueue
     */
    public Event evt;

    /* table for mapping old Event action keys to KeyEvent virtual keys. */
    private static final int[][] actionKeyCodes = {
            /*    virtual key              action key   */
            { KeyEvent.VK_HOME, Event.HOME }, { KeyEvent.VK_END, Event.END }, { KeyEvent.VK_PAGE_UP, Event.PGUP },
            { KeyEvent.VK_PAGE_DOWN, Event.PGDN }, { KeyEvent.VK_UP, Event.UP }, { KeyEvent.VK_DOWN, Event.DOWN },
            { KeyEvent.VK_LEFT, Event.LEFT }, { KeyEvent.VK_RIGHT, Event.RIGHT }, { KeyEvent.VK_F1, Event.F1 },
            { KeyEvent.VK_F2, Event.F2 }, { KeyEvent.VK_F3, Event.F3 }, { KeyEvent.VK_F4, Event.F4 },
            { KeyEvent.VK_F5, Event.F5 }, { KeyEvent.VK_F6, Event.F6 }, { KeyEvent.VK_F7, Event.F7 },
            { KeyEvent.VK_F8, Event.F8 }, { KeyEvent.VK_F9, Event.F9 }, { KeyEvent.VK_F10, Event.F10 },
            { KeyEvent.VK_F11, Event.F11 }, { KeyEvent.VK_F12, Event.F12 },
            { KeyEvent.VK_PRINTSCREEN, Event.PRINT_SCREEN }, { KeyEvent.VK_SCROLL_LOCK, Event.SCROLL_LOCK },
            { KeyEvent.VK_CAPS_LOCK, Event.CAPS_LOCK }, { KeyEvent.VK_NUM_LOCK, Event.NUM_LOCK },
            { KeyEvent.VK_PAUSE, Event.PAUSE }, { KeyEvent.VK_INSERT, Event.INSERT } };

    /**
     * This field controls whether or not the event is sent back
     * down to the peer once the target has processed it -
     * false means it's sent to the peer, true means it's not.
     *
     * @serial
     * @see #isConsumed()
     */
    private boolean consumed = false;

    /*
     * JDK 1.1 serialVersionUID
     */
    private static final long serialVersionUID = 5488922509400504703L;

    static {
        /* ensure that the necessary native libraries are loaded */
        Toolkit.loadLibraries();
        if (!GraphicsEnvironment.isHeadless()) {
            initIDs();
        }
    }

    /**
     * Initialize JNI field and method IDs for fields that may be
       accessed from C.
     */
    private static native void initIDs();

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Creates an instance of {@code Event} with the specified target
     * component, time stamp, event type, <i>x</i> and <i>y</i>
     * coordinates, keyboard key, state of the modifier keys, and
     * argument.
     * @param     target     the target component.
     * @param     when       the time stamp.
     * @param     id         the event type.
     * @param     x          the <i>x</i> coordinate.
     * @param     y          the <i>y</i> coordinate.
     * @param     key        the key pressed in a keyboard event.
     * @param     modifiers  the state of the modifier keys.
     * @param     arg        the specified argument.
     */
    public Event(Object target, long when, int id, int x, int y, int key, int modifiers, Object arg) {
        this.target = target;
        this.when = when;
        this.id = id;
        this.x = x;
        this.y = y;
        this.key = key;
        this.modifiers = modifiers;
        this.arg = arg;
        this.data = 0;
        this.clickCount = 0;
        switch (id) {
        case ACTION_EVENT:
        case WINDOW_DESTROY:
        case WINDOW_ICONIFY:
        case WINDOW_DEICONIFY:
        case WINDOW_MOVED:
        case SCROLL_LINE_UP:
        case SCROLL_LINE_DOWN:
        case SCROLL_PAGE_UP:
        case SCROLL_PAGE_DOWN:
        case SCROLL_ABSOLUTE:
        case SCROLL_BEGIN:
        case SCROLL_END:
        case LIST_SELECT:
        case LIST_DESELECT:
            consumed = true; // these types are not passed back to peer
            break;
        default:
        }
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Creates an instance of {@code Event}, with the specified target
     * component, time stamp, event type, <i>x</i> and <i>y</i>
     * coordinates, keyboard key, state of the modifier keys, and an
     * argument set to {@code null}.
     * @param     target     the target component.
     * @param     when       the time stamp.
     * @param     id         the event type.
     * @param     x          the <i>x</i> coordinate.
     * @param     y          the <i>y</i> coordinate.
     * @param     key        the key pressed in a keyboard event.
     * @param     modifiers  the state of the modifier keys.
     */
    public Event(Object target, long when, int id, int x, int y, int key, int modifiers) {
        this(target, when, id, x, y, key, modifiers, null);
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Creates an instance of {@code Event} with the specified
     * target component, event type, and argument.
     * @param     target     the target component.
     * @param     id         the event type.
     * @param     arg        the specified argument.
     */
    public Event(Object target, int id, Object arg) {
        this(target, 0, id, 0, 0, 0, 0, arg);
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Translates this event so that its <i>x</i> and <i>y</i>
     * coordinates are increased by <i>dx</i> and <i>dy</i>,
     * respectively.
     * <p>
     * This method translates an event relative to the given component.
     * This involves, at a minimum, translating the coordinates into the
     * local coordinate system of the given component. It may also involve
     * translating a region in the case of an expose event.
     * @param     dx     the distance to translate the <i>x</i> coordinate.
     * @param     dy     the distance to translate the <i>y</i> coordinate.
     */
    public void translate(int dx, int dy) {
        this.x += dx;
        this.y += dy;
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Checks if the Shift key is down.
     * @return    {@code true} if the key is down;
     *            {@code false} otherwise.
     * @see       java.awt.Event#modifiers
     * @see       java.awt.Event#controlDown
     * @see       java.awt.Event#metaDown
     */
    public boolean shiftDown() {
        return (modifiers & SHIFT_MASK) != 0;
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Checks if the Control key is down.
     * @return    {@code true} if the key is down;
     *            {@code false} otherwise.
     * @see       java.awt.Event#modifiers
     * @see       java.awt.Event#shiftDown
     * @see       java.awt.Event#metaDown
     */
    public boolean controlDown() {
        return (modifiers & CTRL_MASK) != 0;
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Checks if the Meta key is down.
     *
     * @return    {@code true} if the key is down;
     *            {@code false} otherwise.
     * @see       java.awt.Event#modifiers
     * @see       java.awt.Event#shiftDown
     * @see       java.awt.Event#controlDown
     */
    public boolean metaDown() {
        return (modifiers & META_MASK) != 0;
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     */
    void consume() {
        switch (id) {
        case KEY_PRESS:
        case KEY_RELEASE:
        case KEY_ACTION:
        case KEY_ACTION_RELEASE:
            consumed = true;
            break;
        default:
            // event type cannot be consumed
        }
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     */
    boolean isConsumed() {
        return consumed;
    }

    /*
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Returns the integer key-code associated with the key in this event,
     * as described in java.awt.Event.
     */
    static int getOldEventKey(KeyEvent e) {
        int keyCode = e.getKeyCode();
        for (int i = 0; i < actionKeyCodes.length; i++) {
            if (actionKeyCodes[i][0] == keyCode) {
                return actionKeyCodes[i][1];
            }
        }
        return (int) e.getKeyChar();
    }

    /*
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Returns a new KeyEvent char which corresponds to the int key
     * of this old event.
     */
    char getKeyEventChar() {
        for (int i = 0; i < actionKeyCodes.length; i++) {
            if (actionKeyCodes[i][1] == key) {
                return KeyEvent.CHAR_UNDEFINED;
            }
        }
        return (char) key;
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Returns a string representing the state of this {@code Event}.
     * This method is intended to be used only for debugging purposes, and the
     * content and format of the returned string may vary between
     * implementations. The returned string may be empty but may not be
     * {@code null}.
     *
     * @return    the parameter string of this event
     */
    protected String paramString() {
        String str = "id=" + id + ",x=" + x + ",y=" + y;
        if (key != 0) {
            str += ",key=" + key;
        }
        if (shiftDown()) {
            str += ",shift";
        }
        if (controlDown()) {
            str += ",control";
        }
        if (metaDown()) {
            str += ",meta";
        }
        if (target != null) {
            str += ",target=" + target;
        }
        if (arg != null) {
            str += ",arg=" + arg;
        }
        return str;
    }

    /**
     * <b>NOTE:</b> The {@code Event} class is obsolete and is
     * available only for backwards compatibility.  It has been replaced
     * by the {@code AWTEvent} class and its subclasses.
     * <p>
     * Returns a representation of this event's values as a string.
     * @return    a string that represents the event and the values
     *                 of its member fields.
     * @see       java.awt.Event#paramString
     * @since     1.1
     */
    public String toString() {
        return getClass().getName() + "[" + paramString() + "]";
    }
}