我目前正在尝试为Android制作一个小游戏。
我尝试测量游戏的两个动作之间的时间，但是当我在调用该currentTimeMillis()方法后尝试调用该方法时，开始时间保持为 0 gameThread.run()（gameThread 是可运行的）。当我在run()通话之前放置它时，它会提供正确的价值。
类游戏视图：
@Override
public void surfaceCreated(SurfaceHolder holder)
{
// at this point the surface is created and we start the gameloop
gameThread.setRunning(true);
gameThread.run();
begin=System.currentTimeMillis();
}
/**
* This is the game update method. It iterates through all the objects and
* calls their update method
*/
public void update()
{
for (GuiElement element : guiElements)
{
element.update();
}
count++;
if (ball.getPosY() >= Statics.DISPLAY_HEIGTH - ball.getRadius())
{
Log.d(TAG, "Displayhoehe : " + Statics.DISPLAY_HEIGTH);
Log.d(TAG, "DisplayfactorHeight : " + Statics.DISPLAY_FACTOR_HEIGHT);
Log.d(TAG, "speedvalue : " + ball.getSpeedY());
Log.d(TAG, "ballradius : " + ball.getRadius());
Log.d(TAG, "am boden mit " + count + " schritten");
gameThread.setRunning(false);
end = System.currentTimeMillis();
Log.d(TAG, "begin, end " + begin + " " + end);
Log.d(TAG, "time " + (end - begin));
}
}
类 GameThread（实现可运行）
public void run()
{
Canvas canvas;
Log.d(TAG, "Starting game loop");
long beginTime; // the time when the cycle begun
long timeDiff; // the time it took for the cycle to execute
int sleepTime; // ms to sleep (<0 if we're behind)
int framesSkipped; // number of frames being skipped
while (running)
{
canvas = null;
// try locking the canvas for exclusive pixel editing in the surface
try
{
canvas = surfaceHolder.lockCanvas();
synchronized (surfaceHolder)
{
beginTime = System.currentTimeMillis();
framesSkipped = 0; // resetting the frames skipped
// update game state
gameView.update();
// draw state to the screen
gameView.draw(canvas);
// calculate how long did the cycle take
timeDiff = System.currentTimeMillis() - beginTime;
// calculate sleep time
sleepTime = (int) (FRAME_PERIOD - timeDiff);
if (sleepTime > 0)
{
// if sleepTime > 0 we're OK
try
{
// send the thread to sleep for a short period very
// (useful for battery saving)
Thread.sleep(sleepTime);
}
catch (InterruptedException e)
{
}
}
while (sleepTime < 0 && framesSkipped < MAX_FRAME_SKIPS)
{
// we need to catch up (skip some draw() calls)
this.gameView.update(); // update without rendering
sleepTime += FRAME_PERIOD; // add frame period to check
// if we catched up
framesSkipped++;
}
}
}
finally
{
// in case of an exception the surface is not left in an inconsistent state
if (canvas != null)
{
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}
编辑：我试图在起点记录 currentMillis() 的返回值，似乎该方法在 run() 方法完成后被调用。它不应该同步运行吗？
@Override
public void surfaceCreated(SurfaceHolder holder)
{
// at this point the surface is created and we start the gameloop
gameThread.setRunning(true);
gameThread.run();
begin=System.currentTimeMillis();
Log.d(TAG, "currentMillis at beginning " + System.currentTimeMillis());
}
日志：
10-21 19:43:17.480: D/GameView(19767): Displayhoehe : 480
10-21 19:43:17.480: D/GameView(19767): DisplayfactorHeight : 1.0
10-21 19:43:17.480: D/GameView(19767): speedvalue : 1.6666666666666667
10-21 19:43:17.480: D/GameView(19767): ballradius : 20
10-21 19:43:17.480: D/GameView(19767): am boden mit 133 schritten
10-21 19:43:17.480: D/GameView(19767): begin, end 0 1350841397483
10-21 19:43:17.480: D/GameView(19767): time 1350841397483
10-21 19:43:17.480: D/GameView(19767): currentMillis at beginning 1350841397484
解决方案：我错误地启动了 Runnable。这是启动 Runnable 的正确方法：
gameThread.setRunning(true);
Thread t = new Thread(gameThread);
t.start();
begin=System.currentTimeMillis();