当我单击“主页”按钮或屏幕方向发生变化时，我的应用程序崩溃了，我尝试了许多解决方案，但没有一个起作用。我已经知道它可能与终止线程有关，但是我在编程中是新手，所以我将不胜感激。
这是代码和logcat。代码非常混乱，因为我尝试从该论坛和其他论坛中实施解决方案
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getActionBar().hide();
setContentView(new GameView(this));
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
}
}`
public class GameView extends SurfaceView implements
SurfaceHolder.Callback {
p private KulaSprite kula;
private PaletkaSprite paletka;
private PaletkaSprite paletka2;
private GameLogic mGameLogic;
private boolean mGameIsRunning = false;
private int punkty = 0;
private String p1 = Integer.toString(punkty);
private int punkty2 = 0;
private String p2 = Integer.toString(punkty2);
private float speed;
Paint paint = new Paint();
public void start() {
if (!mGameIsRunning) {
mGameLogic.setGameState(GameLogic.RUNNING);
mGameLogic.start();
mGameIsRunning = true;
} else {
mGameLogic.onResume();
}
}
public GameView(Context context) {
super(context);
setFocusable(true);
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
Point size = new Point();
display.getSize(size);
int width = size.x;
int height = size.y;
kula = new KulaSprite(BitmapFactory.decodeResource(getResources(), R.drawable.kula), 600,300);
paletka = new PaletkaSprite(BitmapFactory.decodeResource(getResources(), R.drawable.paletka),15,height/2);
paletka2 = new PaletkaSprite(BitmapFactory.decodeResource(getResources(), R.drawable.paletka2), width-15,height/2);
mGameLogic = new GameLogic(getHolder(), this);
getHolder().addCallback(this);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height){
}
@Override
public void surfaceCreated(SurfaceHolder holder){
start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder){
}
public void onDraw(Canvas canvas) {
canvas.drawColor(Color.rgb(00, 60, 10));
paint.setTextSize((getHeight()*2)/3);
paint.setColor(Color.rgb(00, 80, 10));
canvas.drawText(p1, getWidth()/12, (getHeight()*3)/4,paint);
canvas.drawText(p2, getWidth()/2, (getHeight()*3)/4,paint);
kula.draw(canvas);
paletka.draw(canvas);
paletka2.draw(canvas);
}
public class GameLogic extends Thread {
private SurfaceHolder _surfaceHolder;
private GameView mGameView;
private int game_state;
public static final int PAUSE = 0;
public static final int READY = 1;
public static final int RUNNING = 2;
private Object mPauseLock = new Object();
private boolean mPaused;
public GameLogic(SurfaceHolder surfaceHolder, GameView mGameView) {
super();
this._surfaceHolder = surfaceHolder;
this.mGameView = mGameView;
}
public void setGameState(int gamestate) {
this.game_state = gamestate;
}
public int getGameState(){
return game_state;
}
public void onPause() {
synchronized (mPauseLock) {
mPaused = true;
}
}
public void onResume() {
synchronized (mPauseLock) {
mPaused = false;
mPauseLock.notifyAll();
}
}
@Override
public void run() {
Canvas canvas;
canvas = null;
while (game_state == RUNNING) {
try {
canvas = this._surfaceHolder.lockCanvas(null);
synchronized (_surfaceHolder) {
this.mGameView.update();
this.mGameView.onDraw(canvas);
}
}
finally {
if (canvas != null) {
_surfaceHolder.unlockCanvasAndPost(canvas);
}
}
synchronized (mPauseLock) {
while (mPaused) {
try {
mPauseLock.wait();
} catch (InterruptedException e) {
}
}
}
}
}
}
03-30 14:19:24.880: D/libEGL(3010): loaded /system/lib/egl/libEGL_tegra.so
03-30 14:19:24.910: D/libEGL(3010): loaded /system/lib/egl/libGLESv1_CM_tegra.so
03-30 14:19:24.920: D/libEGL(3010): loaded /system/lib/egl/libGLESv2_tegra.so
03-30 14:19:24.960: D/OpenGLRenderer(3010): Enabling debug mode 0
03-30 14:19:29.270: W/dalvikvm(3010): threadid=11: thread exiting with uncaught exception (group=0x41703ba8)
03-30 14:19:29.270: E/AndroidRuntime(3010): FATAL EXCEPTION: Thread-2715
03-30 14:19:29.270: E/AndroidRuntime(3010): Process: com.pingpong, PID: 3010
03-30 14:19:29.270: E/AndroidRuntime(3010): java.lang.NullPointerException
03-30 14:19:29.270: E/AndroidRuntime(3010): at com.GameView.onDraw(GameView.java:88)
03-30 14:19:29.270: E/AndroidRuntime(3010): at com.pingpong.GameLogic.run(GameLogic.java:60)
最佳答案
按下后退按钮或旋转设备将使活动重新创建。由于您正在制作游戏，因此将屏幕锁定到该活动的AndroidManifest文件中所需的方向上，以便方向更改不会触发它。
http://developer.android.com/guide/topics/manifest/activity-element.html
要处理用户退出（后退或主页按下）的操作，您需要覆盖活动中的onPause()或onStop()并停止执行游戏循环。由于它们位于单独的线程中，因此无论您是否处于活动中，循环都将继续执行。