Java Android游戏循环不顺畅

试图使非常简单的游戏循环，一个球在屏幕上（使用插值）

游戏循环：

    private double FPS = 50;
    private double TIME_STEP = 1000000000L/FPS;
    private double MAX_TIME = 1000000000L/5;

    Canvas canvas;

    double frameStart = System.nanoTime();
    double currentTime = 0;
    double accumulator = 0;
    float ratio = 0;

    while (running){

        currentTime = System.nanoTime();
        accumulator += currentTime - frameStart;

        frameStart = currentTime;

        if(accumulator > MAX_TIME){
            accumulator = MAX_TIME;
        }

        while (accumulator > TIME_STEP){
            screen.update();
            accumulator -= TIME_STEP;
        }

        ratio = Math.min(1f, (float)(accumulator / TIME_STEP));

        canvas = surfaceHolder.lockCanvas();
        screen.render(ratio, canvas);
        surfaceHolder.unlockCanvasAndPost(canvas);

    }

更新方法：

public void update(){
    pY = cY;
    cY -= 0.1f
}

渲染方法：

public void render(float ratio, Canvas canvas){
    canvas.drawCircle(cX * ratio + pX * (1 - ratio),
            cY * ratio + pY * (1 - ratio),
            cR * ratio + pR * (1 - ratio), paint);
}

这一切都在我的设备上运行，为什么？我将FPS更改为25和60，但仍然不平滑。没有插值，游戏循环看起来更好，但这是错误的方式