解决J2ME开发中的连续按键问题（2）

解决J2ME开发中的连续按键问题（2）
下面是应用程序截图和源代码。

package com.j2medev;

import javax.microedition.lcdui.*;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class KeyActionMIDlet extends MIDlet
{

private Display display;

private MainCanvas mainCanvas;

protected void startApp() throws MIDletStateChangeException
{

display = Display.getDisplay(this);
mainCanvas = new MainCanvas();
new Thread(mainCanvas).start();
display.setCurrent(mainCanvas);

}

protected void pauseApp()
{
}

protected void destroyApp(boolean arg0) throws MIDletStateChangeException
{
}
}

package com.j2medev;

import javax.microedition.lcdui.*;

public class MainCanvas extends Canvas implements Runnable
{
private String buttonPressed;
private boolean leftPressed;
private boolean rightPressed;
private int px = getWidth() / 2;
public final int py = getHeight() / 2;

public MainCanvas()
{
buttonPressed = " ";
}

private void left()
{
if (px >= 0)
{
px--;
}
buttonPressed = "LEFT";
repaint();
}

private void right()
{
if (px <= getWidth())
{
px++;
}
buttonPressed = "RIGHT";
repaint();
}

public void run()
{
while (true)
{
if (leftPressed)
{
left();
}
if (rightPressed)
{
right();
}

try
{
Thread.sleep(50);
} catch (InterruptedException e)
{
e.printStackTrace();
}
}
}
public void paint(Graphics g)
{
g.setColor(0xFFFFFF);
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(0x000000);

g.drawString(buttonPressed, 20, 20, Graphics.LEFT | Graphics.TOP);
g.drawString("J2ME", px, py, Graphics.HCENTER | Graphics.TOP);
}

public void keyReleased(int keyCode)
{
int action = getGameAction(keyCode);
switch (action)
{
case LEFT:
leftPressed = false;
buttonPressed = "";
break;
case RIGHT:
rightPressed = false;
buttonPressed = "";
break;
default:
break;
}
repaint();
}
public void keyPressed(int keyCode)
{
int action = getGameAction(keyCode);

switch (action)
{
case LEFT:
left();
leftPressed = true;
break;

case RIGHT:
right();
rightPressed = true;
break;

default:
break;
}
repaint();

}
public void keyRepeated(int keyCode)
{
int action = getGameAction(keyCode);
switch (action)
{
case LEFT:
left();
break;
case RIGHT:
right();
break;

default:
break;
}
repaint();
}
}

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