java Android线程睡眠不准确

Question

我尝试通过安卓 emulator和jvm运行这段代码。 在JVM上，它的睡眠时间应该是33-34毫秒，而在安卓上则是68-85毫秒。 为什么这么不准确

谢谢你的帮助

package 安卓.apps.td;

公共类逻辑实现可运行{

private long frame_time = 1000000000/30;
private long offset = 0;
private long timestamp = 0;

public void run(){
    long step;
    while(true){
        step = System.nanoTime();
        if((offset = (step - timestamp)) > frame_time){
            System.out.println("FRAME     "+(step - timestamp)/1000000+" ms");
            timestamp = step;
            update();
            render();
            repaint();
            try {
                Thread.sleep(frame_time/1000000+1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }else{
            try {
                System.out.println("Sleep ["+((frame_time-offset)/1000000+1)+" ms]");

                Thread.sleep(((frame_time-offset)/1000000+1));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

private void update() {
}

private void render() {
}

private void repaint() {
}

}