Applet event tester : Applet « Swing JFC « Java

Applet event tester

Applet event tester
//File: applet.html
<applet code="EventTester.class"
  width=400 height=400>

 * Copyright (c) 2000 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 2nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book (recommended),
 * visit

import java.applet.Applet;
import java.awt.Event;
import java.awt.Graphics;
import java.util.Vector;

/** An applet that gives details about Java 1.0 events */
public class EventTester extends Applet {
  // Handle mouse events
  public boolean mouseDown(Event e, int x, int y) {
    showLine(mods(e.modifiers) + "Mouse Down: [" + x + "," + y + "]");
    return true;

  public boolean mouseUp(Event e, int x, int y) {
    showLine(mods(e.modifiers) + "Mouse Up: [" + x + "," + y + "]");
    return true;

  public boolean mouseDrag(Event e, int x, int y) {
    showLine(mods(e.modifiers) + "Mouse Drag: [" + x + "," + y + "]");
    return true;

  public boolean mouseMove(Event e, int x, int y) {
    showLine(mods(e.modifiers) + "Mouse Move: [" + x + "," + y + "]");
    return true;

  public boolean mouseEnter(Event e, int x, int y) {
    showLine("Mouse Enter: [" + x + "," + y + "]");
    return true;

  public boolean mouseExit(Event e, int x, int y) {
    showLine("Mouse Exit: [" + x + "," + y + "]");
    return true;

  // Handle focus events
  public boolean gotFocus(Event e, Object what) {
    showLine("Got Focus");
    return true;

  public boolean lostFocus(Event e, Object what) {
    showLine("Lost Focus");
    return true;

  // Handle key down and key up events
  // This gets more confusing because there are two types of key events
  public boolean keyDown(Event e, int key) {
    int flags = e.modifiers;
    if ( == Event.KEY_PRESS) // a regular key
      showLine("Key Down: " + mods(flags) + key_name(e));
    else if ( == Event.KEY_ACTION) // a function key
      showLine("Function Key Down: " + mods(flags)
          + function_key_name(key));
    return true;

  public boolean keyUp(Event e, int key) {
    int flags = e.modifiers;
    if ( == Event.KEY_RELEASE) // a regular key
      showLine("Key Up: " + mods(flags) + key_name(e));
    else if ( == Event.KEY_ACTION_RELEASE) // a function key
      showLine("Function Key Up: " + mods(flags) + function_key_name(key));
    return true;

  // The remaining methods help us sort out the various modifiers and keys

  // Return the current list of modifier keys
  private String mods(int flags) {
    String s = "[ ";
    if (flags == 0)
      return "";
    if ((flags & Event.SHIFT_MASK) != 0)
      s += "Shift ";
    if ((flags & Event.CTRL_MASK) != 0)
      s += "Control ";
    if ((flags & Event.META_MASK) != 0)
      s += "Meta ";
    if ((flags & Event.ALT_MASK) != 0)
      s += "Alt ";
    s += "] ";
    return s;

  // Return the name of a regular (non-function) key.
  private String key_name(Event e) {
    char c = (char) e.key;
    if (e.controlDown()) { // If CTRL flag is set, handle control chars.
      if (c < ' ') {
        c += '@';
        return "^" + c;
    } else { // If CTRL flag is not set, then certain ASCII
      switch (c) { // control characters have special meaning.
      case '\n':
        return "Return";
      case '\t':
        return "Tab";
      case '\033':
        return "Escape";
      case '\010':
        return "Backspace";
    // Handle the remaining possibilities.
    if (c == '\177')
      return "Delete";
    else if (c == ' ')
      return "Space";
      return String.valueOf(c);

  // Return the name of a function key. Just compare the key to the
  // constants defined in the Event class.
  private String function_key_name(int key) {
    switch (key) {
    case Event.HOME:
      return "Home";
    case Event.END:
      return "End";
    case Event.PGUP:
      return "Page Up";
    case Event.PGDN:
      return "Page Down";
    case Event.UP:
      return "Up";
    case Event.DOWN:
      return "Down";
    case Event.LEFT:
      return "Left";
    case Event.RIGHT:
      return "Right";
    case Event.F1:
      return "F1";
    case Event.F2:
      return "F2";
    case Event.F3:
      return "F3";
    case Event.F4:
      return "F4";
    case Event.F5:
      return "F5";
    case Event.F6:
      return "F6";
    case Event.F7:
      return "F7";
    case Event.F8:
      return "F8";
    case Event.F9:
      return "F9";
    case Event.F10:
      return "F10";
    case Event.F11:
      return "F11";
    case Event.F12:
      return "F12";
    return "Unknown Function Key";

  /** A list of lines to display in the window */
  protected Vector lines = new Vector();

  /** Add a new line to the list of lines, and redisplay */
  protected void showLine(String s) {
    if (lines.size() == 20)

  /** This method repaints the text in the window */
  public void paint(Graphics g) {
    for (int i = 0; i < lines.size(); i++)
      g.drawString((String) lines.elementAt(i), 20, i * 16 + 50);


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