Android毫秒

Question

所以我正在尝试编写一个秒表应用程序,以毫秒为单位显示时间,但由于某种原因它不起作用.基本上我只有一个togglebutton,按下后,开始打印从开始时间到当前时间的毫秒......但在模拟器中,应用程序锁定.怎么了？

public class testing extends Activity {
/** Called when the activity is first created. */
Button start,stop;
long init,now,time;
TextView display;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.test);
    display = (TextView) findViewById(R.id.chronometer1);
    final ToggleButton passTog = (ToggleButton) findViewById(R.id.onoff);
    passTog.setOnClickListener(new View.OnClickListener() {

        public void onClick(View v) {
            init=System.currentTimeMillis();
            while(passTog.isChecked())
            {
                now=System.currentTimeMillis();
                time=now-init;
                display.setText("t: " + time);
            }

        }
    });
}

}

Answer 1

你绝对不应该像在OnClickListener中那样运行繁忙的循环.这就是应用程序锁定的原因.你需要让系统的其余部分发表意见.此外,每30毫秒左右更新一次显示器是没有意义的,因为这是人眼可以跟踪的最快速度.此外,您可能希望在活动暂停时暂停计时器.这是一个完成所有这些的版本:

public class testing extends Activity {

    /** Called when the activity is first created. */
    Button start,stop;
    long init,now,time,paused;
    TextView display;
    Handler handler;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        handler = new Handler();
        setContentView(R.layout.test);
        display = (TextView) findViewById(R.id.chronometer1);
        final ToggleButton passTog = (ToggleButton) findViewById(R.id.onoff);
        final Runnable updater = new Runnable() {
            @Override
            public void run() {
                if (passTog.isChecked()) {
                    now=System.currentTimeMillis();
                    time=now-init;
                    display.setText("t: " + time);
                    handler.postDelayed(this, 30);
                }
            }
        };
        passTog.setOnClickListener(new View.OnClickListener() {

            public void onClick(View v) {
                init = System.currentTimeMillis();
                handler.post(updater);
            }
        });
    }

    @Override
    protected void onPause() {
        super.onPause();
        paused = System.currentTimeMillis();
    }

    @Override
    protected void onResume() {
        super.onResume();
        init += System.currentTimeMillis() - paused;
    }
}