Java/J2ME/Key Event
Содержание
Canvas for processing game actions
/*--------------------------------------------------
* GameActions.java
*
* Canvas for processing game actions
*
* Example from the book: Core J2ME Technology
* Copyright John W. Muchow http://www.CoreJ2ME.ru
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class GameActions extends MIDlet
{
private Display display; // The display
private GameActionCanvas canvas; // Canvas
public GameActions()
{
display = Display.getDisplay(this);
canvas = new GameActionCanvas(this);
}
protected void startApp()
{
display.setCurrent( canvas );
}
protected void pauseApp()
{ }
protected void destroyApp( boolean unconditional )
{ }
public void exitMIDlet()
{
destroyApp(true);
notifyDestroyed();
}
}
/*--------------------------------------------------
* GameActionCanvas.java
*
* Game action event handling
*-------------------------------------------------*/
class GameActionCanvas extends Canvas implements CommandListener
{
private Command cmExit; // Exit midlet
private String keyText = null; // Key code text
private GameActions midlet;
/*--------------------------------------------------
* Constructor
*-------------------------------------------------*/
public GameActionCanvas(GameActions midlet)
{
this.midlet = midlet;
// Create exit command & listen for events
cmExit = new Command("Exit", Command.EXIT, 1);
addCommand(cmExit);
setCommandListener(this);
}
/*--------------------------------------------------
* Paint the text representing the key code
*-------------------------------------------------*/
protected void paint(Graphics g)
{
// Clear the background (to white)
g.setColor(255, 255, 255);
g.fillRect(0, 0, getWidth(), getHeight());
// Set color and draw text
if (keyText != null)
{
// Draw with black pen
g.setColor(0, 0, 0);
// Center the text
g.drawString(keyText, getWidth()/2, getHeight()/2, Graphics.TOP | Graphics.HCENTER);
}
}
/*--------------------------------------------------
* Command event handling
*-------------------------------------------------*/
public void commandAction(Command c, Displayable d)
{
if (c == cmExit)
midlet.exitMIDlet();
}
/*--------------------------------------------------
* Game action event handling
* A game action will be converted into a key code
* and handed off to this method
*-------------------------------------------------*/
protected void keyPressed(int keyCode)
{
switch (getGameAction(keyCode))
{
// Place logic of each action inside the case
case FIRE:
case UP:
case DOWN:
case LEFT:
case RIGHT:
case GAME_A:
case GAME_B:
case GAME_C:
case GAME_D:
default:
// Print the text of the game action
keyText = getKeyName(keyCode);
}
repaint();
}
}
Canvas for processing key code and commands
/*--------------------------------------------------
* KeyCodes.java
*
* Canvas for processing key code and commands
*
* Example from the book: Core J2ME Technology
* Copyright John W. Muchow http://www.CoreJ2ME.ru
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class KeyCodes extends MIDlet
{
private Display display; // The display
private KeyCodeCanvas canvas; // Canvas
public KeyCodes()
{
display = Display.getDisplay(this);
canvas = new KeyCodeCanvas(this);
}
protected void startApp()
{
display.setCurrent( canvas );
}
protected void pauseApp()
{ }
protected void destroyApp( boolean unconditional )
{ }
public void exitMIDlet()
{
destroyApp(true);
notifyDestroyed();
}
}
/*--------------------------------------------------
* Class KeyCodeCanvas
*
* Key codes and commands for event handling
*-------------------------------------------------*/
class KeyCodeCanvas extends Canvas implements CommandListener
{
private Command cmExit; // Exit midlet
private String keyText = null; // Key code text
private KeyCodes midlet;
/*--------------------------------------------------
* Constructor
*-------------------------------------------------*/
public KeyCodeCanvas(KeyCodes midlet)
{
this.midlet = midlet;
// Create exit command & listen for events
cmExit = new Command("Exit", Command.EXIT, 1);
addCommand(cmExit);
setCommandListener(this);
}
/*--------------------------------------------------
* Paint the text representing the key code
*-------------------------------------------------*/
protected void paint(Graphics g)
{
// Clear the background (to white)
g.setColor(255, 255, 255);
g.fillRect(0, 0, getWidth(), getHeight());
// Set color and draw text
if (keyText != null)
{
// Draw with black pen
g.setColor(0, 0, 0);
// Close to the center
g.drawString(keyText, getWidth()/2, getHeight()/2, Graphics.TOP | Graphics.HCENTER);
}
}
/*--------------------------------------------------
* Command event handling
*-------------------------------------------------*/
public void commandAction(Command c, Displayable d)
{
if (c == cmExit)
midlet.exitMIDlet();
}
/*--------------------------------------------------
* Key code event handling
*-------------------------------------------------*/
protected void keyPressed(int keyCode)
{
keyText = getKeyName(keyCode);
repaint();
}
}
Event Example 1
/* License
*
* Copyright 1994-2004 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistribution of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistribution in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
public class EventEx1 extends MIDlet implements CommandListener {
// display manager
Display display = null;
// a menu with items
List menu = null; // main menu
// textbox
TextBox input = null;
// command
static final Command backCommand = new Command("Back", Command.BACK, 0);
static final Command mainMenuCommand = new Command("Main", Command.SCREEN, 1);
static final Command exitCommand = new Command("Exit", Command.STOP, 2);
String currentMenu = null;
// constructor.
public EventEx1() {
}
/**
* Start the MIDlet by creating a list of items and associating the
* exit command with it.
*/
public void startApp() throws MIDletStateChangeException {
display = Display.getDisplay(this);
menu = new List("Menu Items", Choice.IMPLICIT);
menu.append("Item1", null);
menu.append("Item2", null);
menu.append("Item3", null);
menu.append("Item4", null);
menu.addCommand(exitCommand);
menu.setCommandListener(this);
mainMenu();
}
public void pauseApp() {
display = null;
menu = null;
input = null;
}
public void destroyApp(boolean unconditional) {
notifyDestroyed();
}
// main menu
void mainMenu() {
display.setCurrent(menu);
currentMenu = "Main";
}
/**
* a generic method that will be called when selected any of
* the items on the list.
*/
public void prepare() {
input = new TextBox("Enter some text: ", "", 5, TextField.ANY);
input.addCommand(backCommand);
input.setCommandListener(this);
input.setString("");
display.setCurrent(input);
}
/**
* Test item1.
*/
public void testItem1() {
prepare();
currentMenu = "item1";
}
/**
* Test item2.
*/
public void testItem2() {
prepare();
currentMenu = "item2";
}
/**
* Test item3.
*/
public void testItem3() {
prepare();
currentMenu = "item3";
}
/**
* Test item4.
*/
public void testItem4() {
prepare();
currentMenu = "item4";
}
/**
* Handle events.
*/
public void commandAction(Command c, Displayable d) {
String label = c.getLabel();
if (label.equals("Exit")) {
destroyApp(true);
} else if (label.equals("Back")) {
if(currentMenu.equals("item1") || currentMenu.equals("item2") ||
currentMenu.equals("item3") || currentMenu.equals("item4")) {
// go back to menu
mainMenu();
}
} else {
List down = (List)display.getCurrent();
switch(down.getSelectedIndex()) {
case 0: testItem1();break;
case 1: testItem2();break;
case 2: testItem3();break;
case 3: testItem4();break;
}
}
}
}
Event Example 2
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class EventEx2 extends MIDlet {
Display display;
public EventEx2() {
display = Display.getDisplay(this);
}
public void destroyApp (boolean unconditional) {
notifyDestroyed();
System.out.println("App destroyed ");
}
public void pauseApp () {
display = null;
System.out.println("App paused.");
}
public void startApp () {
Form form = new Form("Change Date");
ItemStateListener listener = new ItemStateListener() {
java.util.Calendar cal =
java.util.Calendar.getInstance(java.util.TimeZone.getDefault());
public void itemStateChanged(Item item) {
cal.setTime(((DateField)item).getDate());
System.out.println("\nDate has changed");
}
};
form.setItemStateListener(listener);
java.util.Date now = new java.util.Date();
DateField dateItem = new DateField("Today"s date:", DateField.DATE);
dateItem.setDate(now);
form.append(dateItem);
display.setCurrent(form);
}
}
Game Key Event
/*
J2ME in a Nutshell
By Kim Topley
ISBN: 0-596-00253-X
*/
import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.rumand;
import javax.microedition.lcdui.rumandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Graphics;
import javax.microedition.midlet.MIDlet;
public class EventsMIDlet extends MIDlet
implements CommandListener {
// The MIDlet"s Display object
private Display display;
// Flag indicating first call of startApp
protected boolean started;
// Exit command
private Command exitCommand;
protected void startApp() {
if (!started) {
display = Display.getDisplay(this);
Canvas canvas = new EventsCanvas();
exitCommand = new Command("Exit", Command.EXIT, 0);
canvas.addCommand(exitCommand);
canvas.setCommandListener(this);
display.setCurrent(canvas);
started = true;
}
}
protected void pauseApp() {
}
protected void destroyApp(boolean unconditional) {
}
public void commandAction(Command c, Displayable d) {
if (c == exitCommand) {
// Exit. No need to call destroyApp
// because it is empty.
notifyDestroyed();
}
}
}
class EventsCanvas extends Canvas {
static int[] keyCodes = {KEY_NUM0, KEY_NUM1, KEY_NUM2, KEY_NUM3, KEY_NUM4,
KEY_NUM5, KEY_NUM6, KEY_NUM7, KEY_NUM8, KEY_NUM9,
KEY_POUND, KEY_STAR};
static String[] keyNames = {"KEY_NUM0", "KEY_NUM1", "KEY_NUM2", "KEY_NUM3", "KEY_NUM4",
"KEY_NUM5", "KEY_NUM6", "KEY_NUM7", "KEY_NUM8", "KEY_NUM9",
"KEY_POUND", "KEY_STAR"};
static int[] gameActions = {
UP, DOWN, LEFT, RIGHT, FIRE,
GAME_A, GAME_B, GAME_C, GAME_D};
static String[] gameNames = {
"UP", "DOWN", "LEFT", "RIGHT", "FIRE",
"GAME_A", "GAME_B", "GAME_C", "GAME_D" };
int lastKeyCode = 0;
int lastX;
int lastY;
boolean pointer;
protected void keyPressed(int keyCode) {
lastKeyCode = keyCode;
repaint();
}
protected void keyRepeated(int keyCode) {
lastKeyCode = keyCode;
repaint();
}
protected void keyReleased(int keyCode) {
lastKeyCode = 0;
repaint();
}
protected void pointerPressed(int x, int y) {
lastX = x;
lastY = y;
pointer = true;
repaint();
}
protected void pointerDragged(int x, int y) {
lastX = x;
lastY = y;
pointer = true;
repaint();
}
protected void pointerReleased(int x, int y) {
pointer = false;
repaint();
}
protected void paint(Graphics g) {
g.setColor(0xffffff);
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(0);
if (lastKeyCode != 0) {
String keyText = "keyCode " + lastKeyCode;
String keyName = null;
// See if it is a standard key
for (int i = 0; i < keyCodes.length; i++) {
if (lastKeyCode == keyCodes[i]) {
keyName = keyNames[i];
break;
}
}
if (keyName == null) {
// See if it is a game action
for (int i = 0; i < gameActions.length; i++) {
if (lastKeyCode == getKeyCode(gameActions[i])) {
keyName = gameNames[i];
break;
}
}
}
g.drawString(keyText, getWidth()/2, getHeight()/2,
Graphics.BASELINE|Graphics.HCENTER);
if (keyName != null) {
g.drawString(keyName, getWidth()/2, getHeight()/2 + g.getFont().getHeight(),
Graphics.BASELINE|Graphics.HCENTER);
}
} else if (pointer) {
g.drawString("(" + lastX + ", " + lastY + ")", getWidth()/2, getHeight()/2,
Graphics.BASELINE|Graphics.HCENTER);
}
}
}
Key Event Demo
/*
* @(#)Tiles.java 1.6 00/05/24 Copyright (c) 2000 Sun Microsystems, Inc. All
* Rights Reserved.
*
* This software is the confidential and proprietary information of Sun
* Microsystems, Inc. ("Confidential Information"). You shall not disclose such
* Confidential Information and shall use it only in accordance with the terms
* of the license agreement you entered into with Sun.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
* SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
* NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY
* LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES.
*/
import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.rumand;
import javax.microedition.lcdui.rumandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;
import javax.microedition.midlet.MIDlet;
public class Tiles extends MIDlet {
Board b;
public Tiles() {
b = new Board(this);
}
public void startApp() {
Display.getDisplay(this).setCurrent(b);
}
public void pauseApp() {
}
public void destroyApp(boolean unconditional) {
}
}
/*
* @(#)Board.java 1.14 00/05/23 Copyright (c) 2000 Sun Microsystems, Inc. All
* Rights Reserved.
*
* This software is the confidential and proprietary information of Sun
* Microsystems, Inc. ("Confidential Information"). You shall not disclose such
* Confidential Information and shall use it only in accordance with the terms
* of the license agreement you entered into with Sun.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
* SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
* NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY
* LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES.
*/
class Board extends Canvas implements CommandListener {
MIDlet midlet;
Command exitCommand;
Font font;
// Character Position
int xPos, yPos;
// Chracter Height and Width in pixels
int charW, charH;
public Board(MIDlet midlet_) {
int i;
midlet = midlet_;
Display dpy = Display.getDisplay(midlet);
int letterWidth = 4;
font = Font.getFont(Font.FACE_SYSTEM, Font.STYLE_PLAIN,
Font.SIZE_MEDIUM);
charW = font.charWidth("M") + 7;
charH = font.getHeight() + 1;
xPos = (getWidth() - (letterWidth * charW) + 1) / 2;
yPos = 1;
exitCommand = new Command("Exit", Command.SCREEN, 2);
addCommand(exitCommand);
setCommandListener(this);
repaint();
}
public void commandAction(Command c, Displayable d) {
if (c == exitCommand) {
midlet.notifyDestroyed();
}
}
public void paint(Graphics g) {
g.setColor(0);
g.drawRect(4, 4, 4 * charW + 2, 4 * charH + 2);
}
public void keyPressed(int code) {
int game = getGameAction(code);
switch (game) {
case Canvas.UP:
System.out.println("Canvas.UP");
break;
case Canvas.DOWN:
System.out.println("Canvas.DOWN");
break;
case Canvas.LEFT:
System.out.println("Canvas.LEFT");
break;
case Canvas.RIGHT:
System.out.println("Canvas.RIGHT");
break;
}
switch (code) {
case Canvas.KEY_NUM0:
System.out.println("Key 0");
break;
case Canvas.KEY_NUM1:
System.out.println("Key 1");
break;
case Canvas.KEY_NUM2:
System.out.println("Key 2");
break;
case Canvas.KEY_NUM3:
System.out.println("Key 3");
break;
case Canvas.KEY_NUM4:
System.out.println("Key 4");
break;
case Canvas.KEY_NUM5:
System.out.println("Key 5");
break;
case Canvas.KEY_NUM6:
System.out.println("Key 6");
break;
case Canvas.KEY_NUM7:
System.out.println("Key 7");
break;
case Canvas.KEY_NUM8:
System.out.println("Key 8");
break;
case Canvas.KEY_NUM9:
System.out.println("Key 9");
break;
case Canvas.KEY_STAR:
System.out.println("Star Key");
break;
case Canvas.KEY_POUND:
System.out.println("Pound Key");
break;
// default:
// System.out.println( "default" );
// return;
}
}
}
Key Event with Canvas
/* License
*
* Copyright 1994-2004 Sun Microsystems, Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistribution of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistribution in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of Sun Microsystems, Inc. or the names of contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* This software is provided "AS IS," without a warranty of any kind. ALL
* EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
* AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
* AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
* DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
* REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
* INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
* OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
* EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
*
* You acknowledge that this software is not designed, licensed or intended
* for use in the design, construction, operation or maintenance of any
* nuclear facility.
*/
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class EventEx3 extends MIDlet {
Display display;
Command exit;
public EventEx3() {
display = Display.getDisplay(this);
}
public void destroyApp (boolean unconditional) {
}
public void pauseApp () {
System.out.println("App paused.");
}
public void startApp () {
display = Display.getDisplay(this);
Canvas canvas = new Canvas() { // anonymous class
public void paint(Graphics g) {
}
protected void keyPressed(int keyCode) {
if (keyCode > 0) {
System.out.println("keyPressed " +((char)keyCode));
} else {
System.out.println("keyPressed action " +getGameAction(keyCode));
}
}
protected void keyReleased(int keyCode) {
if (keyCode > 0) {
System.out.println("keyReleased " +((char)keyCode));
} else {
System.out.println("keyReleased action " +getGameAction(keyCode));
}
}
}; // end of anonymous class
exit = new Command("Exit", Command.STOP, 1);
canvas.addCommand(exit);
canvas.setCommandListener(new CommandListener() {
public void commandAction(Command c, Displayable d) {
if(c == exit) {
notifyDestroyed();
} else {
System.out.println("Saw the command: "+c);
}
}
});
display.setCurrent(canvas);
}
}
Key MIDlet
import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.rumand;
import javax.microedition.lcdui.rumandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;
import javax.microedition.midlet.MIDlet;
public class KeyMIDlet extends MIDlet {
public void startApp() {
Displayable d = new KeyCanvas();
d.addCommand(new Command("Exit", Command.EXIT, 0));
d.setCommandListener(new CommandListener() {
public void commandAction(Command c, Displayable s) {
notifyDestroyed();
}
});
Display.getDisplay(this).setCurrent(d);
}
public void pauseApp() {
}
public void destroyApp(boolean unconditional) {
}
}
class KeyCanvas extends Canvas {
private Font mFont = Font.getFont(Font.FACE_PROPORTIONAL, Font.STYLE_PLAIN, Font.SIZE_MEDIUM);
private String mMessage = "[Press keys]";
public KeyCanvas() {
}
public void paint(Graphics g) {
int w = getWidth();
int h = getHeight();
g.setGrayScale(255);
g.fillRect(0, 0, w - 1, h - 1);
g.setGrayScale(0);
g.drawRect(0, 0, w - 1, h - 1);
g.setFont(mFont);
int x = w / 2;
int y = h / 2;
g.drawString(mMessage, x, y, Graphics.BASELINE | Graphics.HCENTER);
}
protected void keyPressed(int keyCode) {
int gameAction = getGameAction(keyCode);
switch (gameAction) {
case UP:
mMessage = "UP";
break;
case DOWN:
mMessage = "DOWN";
break;
case LEFT:
mMessage = "LEFT";
break;
case RIGHT:
mMessage = "RIGHT";
break;
case FIRE:
mMessage = "FIRE";
break;
case GAME_A:
mMessage = "GAME_A";
break;
case GAME_B:
mMessage = "GAME_B";
break;
case GAME_C:
mMessage = "GAME_C";
break;
case GAME_D:
mMessage = "GAME_D";
break;
default:
mMessage = "";
break;
}
repaint();
}
}
Low-Level Display Canvas:Key Code Example
/*
J2ME: The Complete Reference
James Keogh
Publisher: McGraw-Hill
ISBN 0072227109
*/
//jad file (please verify the jar size)
/*
MIDlet-Name: KeyCodeExample
MIDlet-Version: 1.0
MIDlet-Vendor: MyCompany
MIDlet-Jar-URL: KeyCodeExample.jar
MIDlet-1: KeyCodeExample, , KeyCodeExample
MicroEdition-Configuration: CLDC-1.0
MicroEdition-Profile: MIDP-1.0
MIDlet-JAR-SIZE: 100
*/
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class KeyCodeExample extends MIDlet
{
private Display display;
private MyCanvas canvas;
public KeyCodeExample ()
{
display = Display.getDisplay(this);
canvas = new MyCanvas(this);
}
protected void startApp()
{
display.setCurrent(canvas);
}
protected void pauseApp()
{
}
protected void destroyApp( boolean unconditional )
{
}
public void exitMIDlet()
{
destroyApp(true);
notifyDestroyed();
}
}
class MyCanvas extends Canvas implements CommandListener
{
private Command exit;
private String direction;
private KeyCodeExample keyCodeExample;
public MyCanvas (KeyCodeExample keyCodeExample)
{
direction = "2=up 8=dn 4=lt 6=rt";
this.keyCodeExample = keyCodeExample;
exit = new Command("Exit", Command.EXIT, 1);
addCommand(exit);
setCommandListener(this);
}
protected void paint(Graphics graphics)
{
graphics.setColor(255,255,255);
graphics.fillRect(0, 0, getWidth(), getHeight());
graphics.setColor(255, 0, 0);
graphics.drawString(direction, 0, 0,
Graphics.TOP | Graphics.LEFT);
}
public void commandAction(Command command, Displayable displayable)
{
if (command == exit)
{
keyCodeExample.exitMIDlet();
}
}
protected void keyPressed(int key)
{
switch ( key ){
case KEY_NUM2:
direction = "up";
break;
case KEY_NUM8:
direction = "down";
break;
case KEY_NUM4:
direction = "left";
break;
case KEY_NUM6:
direction = "right";
break;
}
repaint();
}
}
