游戏循环不能正常工作

Question

我正在编写一个游戏循环（现在），以保持稳定的25 fps。目前我正在测量~37-40。我不知道fps是否实际关闭或者它是否是测量错误。谁能告诉我什么错了？

@Override
protected void onDraw(Canvas canvas) {
    mGameController.update();
    mGameRenderer.render(canvas);
    elapsedTime = System.currentTimeMillis() - currentTime;
    currentTime = System.currentTimeMillis();

    // Game loop
    if (currentTime >= nextGameWorldUpdateTime) {
        long millisecondsPerFrame = 40;
        nextGameWorldUpdateTime = (currentTime + millisecondsPerFrame);
        invalidate();
    } else {
        try {
            long sleepTime = nextGameWorldUpdateTime - currentTime;
            Thread.sleep(sleepTime);
            invalidate();
        } catch (InterruptedException e) {
        }
    }
    canvas.drawText(Long.toString(fps()), mGameAssets.getScreenWidth(), mGreyPaint.getTextSize() + mGameAssets.getStatusbarHeight(), mGreyPaint);
}

private long fps() {
    // Fps
    fpsSamples.addLast(elapsedTime);
    fpsSum += fpsSamples.getLast();
    if (fpsSamples.size() > 100) {
        fpsSum -= fpsSamples.getFirst();
        fpsSamples.removeFirst();
    }
    long averageTimePerFrame = fpsSum / fpsSamples.size();
    return 1000 / averageTimePerFrame;
}