完整程序如下：
import javax.microedition.lcdui.*;
import javax.microedition.lcdui.game.*;
public class TankGameCanvas1 extends GameCanvas implements Runnable {
// 控制方向：
private static int INDEX_OF_UP = 0;
private static int INDEX_OF_DOWN = 1;
private static int INDEX_OF_LEFT = 3;
private static int INDEX_OF_RIGHT = 2;
private boolean isPlay; // Game Loop runs when isPlay is true
private long delay; // To give thread consistency
private int currentX, currentY; // To hold current position of the 'X '
private int width; // To hold screen width
private int height; // To hold screen height
private Sprite spriteTank; // our sprite!
// Constructor and initialization
public TankGameCanvas1() {
super(true);
width = getWidth();
height = getHeight();
currentX = width / 2;
currentY = height / 2;
delay = 20;
// init sprite:
try {
Image image = Image.createImage( "/res/img/ai.png "); // 注意路径
spriteTank = new Sprite(image, 40,50); // 大小是16x16
} catch (Exception e) {
e.printStackTrace();
}
}
// Automatically start thread for game loop
public void start() {
isPlay = true;
new Thread(this).start();
}
public void stop() {
isPlay = false;
}
// Main Game Loop
public void run() {
Graphics g = getGraphics();
while (isPlay) {
input();
drawScreen(g);
try {
Thread.sleep(delay);
} catch (InterruptedException ie) {
}
}
}
// Method to Handle User Inputs
private void input() {
int keyStates = getKeyStates();
// Left
if ((keyStates & LEFT_PRESSED) != 0) {
currentX = Math.max(0, currentX - 1);
spriteTank.setFrame(INDEX_OF_LEFT);
}
// Right
if ((keyStates & RIGHT_PRESSED) !=0 ) {
if ( currentX + 5 < width)
currentX = Math.min(width, currentX + 1);
spriteTank.setFrame(INDEX_OF_RIGHT);
}
// Up
if ((keyStates & UP_PRESSED) != 0) {
currentY = Math.max(0, currentY - 1);
spriteTank.setFrame(INDEX_OF_UP);
}
// Down
if ((keyStates & DOWN_PRESSED) !=0) {
if ( currentY + 10 < height)
currentY = Math.min(height, currentY + 1);
spriteTank.setFrame(INDEX_OF_DOWN);
}
}
// Method to Display Graphics