如何在Android中设置计时器

标准的Java方式使用计时器 java.util.Timer 和 java.util.TimerTask 在Android中工作得很好,但是您应该知道这个方法创建了一个新的线程。

您可以考虑使用非常方便的 Handler 类(android.os.handler)并通过 sendMessageAtTime(android.os.Message, long) 或 sendMessageDelayed(android.os.Message, long) . 一旦收到消息,就可以运行所需的任务。第二种选择是创建 Runnable 对象并通过处理程序的函数对其进行调度 postAtTime(java.lang.Runnable, long) 或 postDelayed(java.lang.Runnable, long) .

是的,JAVA的计时器 可以使用 但问题是 更好的方法 (手机)这是解释 Here .

为了StackOverflow:

自从 Timer 创建一个新线程,它可能被认为很重,

如果您只需要在活动运行时回拨 Handler 可与

Runnable :

private final int interval = 1000; // 1 Second
private Handler handler = new Handler();
private Runnable runnable = new Runnable(){
    public void run() {
        Toast.makeText(MyActivity.this, "C'Mom no hands!", Toast.LENGTH_SHORT).show();
    }
};
...
handler.postAtTime(runnable, System.currentTimeMillis()+interval);
handler.postDelayed(runnable, interval);

或A Message

private final int EVENT1 = 1; 
private Handler handler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        switch (msg.what) {         
        case Event1:
            Toast.makeText(MyActivity.this, "Event 1", Toast.LENGTH_SHORT).show();
            break;

        default:
            Toast.makeText(MyActivity.this, "Unhandled", Toast.LENGTH_SHORT).show();
            break;
        }
    }
};

...

Message msg = handler.obtainMessage(EVENT1);
handler.sendMessageAtTime(msg, System.currentTimeMillis()+interval);
handler.sendMessageDelayed(msg, interval);

另一方面,如果您想从另一个线程在UI线程中运行一段代码,可以使用这种方法。

如果您需要回电,即使您的活动没有运行,那么您可以使用 AlarmManager

正如我所见, java.util.Timer 最常用于实现计时器。

对于重复任务:

new Timer().scheduleAtFixedRate(task, after, interval);

对于单个任务运行:

new Timer().schedule(task, after);

任务 是要执行的方法
之后 初始执行时间
( 间隔 重复执行的时间)

希望这一点有所帮助,可以少花点力气来落实, Android CountDownTimer class

例如

 new CountDownTimer(30000, 1000) {
      public void onTick(long millisUntilFinished) {
          mTextField.setText("seconds remaining: " + millisUntilFinished / 1000);
      }

      public void onFinish() {
          mTextField.setText("done!");
      }  
}.start();

可能 Timerconcept

new CountDownTimer(40000, 1000) { //40000 milli seconds is total time, 1000 milli seconds is time interval

 public void onTick(long millisUntilFinished) {
  }
  public void onFinish() {
 }
}.start();

或

方法2:

编程定时器

添加一个名为time的int新变量。设置为0。 将以下代码添加到mainactivity.java中的oncreate函数中。

//Declare the timer
Timer t = new Timer();
//Set the schedule function and rate
t.scheduleAtFixedRate(new TimerTask() {

    @Override
    public void run() {
        //Called each time when 1000 milliseconds (1 second) (the period parameter)
    }

},
//Set how long before to start calling the TimerTask (in milliseconds)
0,
//Set the amount of time between each execution (in milliseconds)
1000);

进入run方法并添加以下代码。

//We must use this function in order to change the text view text
runOnUiThread(new Runnable() {

    @Override
    public void run() {
        TextView tv = (TextView) findViewById(R.id.main_timer_text);
        tv.setText(String.valueOf(time));
        time += 1;
    }

});

它是情境的。

Android文档建议您使用 AlarmManager 注册在应用程序可能不运行时在指定时间激发的意图。

否则,您应该使用处理程序。

注意:报警管理器是用于 如果你想要 应用程序代码在特定的 时间,即使你的申请没有 当前正在运行。对于正常定时 操作(计时、超时等)IT 更容易更有效地 使用汉德勒。

我们走了…我们需要两节课。我正在发布一个代码,每5秒(5000毫秒)更改一次移动音频配置文件…

我们的第一课

public class ChangeProfileActivityMain extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);

        Timer timer = new Timer();
        TimerTask updateProfile = new CustomTimerTask(ChangeProfileActivityMain.this);
        timer.scheduleAtFixedRate(updateProfile, 0, 5000);
    }

}

我们的第二课

public class CustomTimerTask extends TimerTask {

    private AudioManager audioManager;
    private Context context;
    private Handler mHandler = new Handler();

    // Write Custom Constructor to pass Context
    public CustomTimerTask(Context con) {
        this.context = con;
    }

    @Override
    public void run() {
        // TODO Auto-generated method stub

        // your code starts here.
        // I have used Thread and Handler as we can not show Toast without starting new thread when we are inside a thread.
        // As TimePicker has run() thread running., So We must show Toast through Handler.post in a new Thread. Thats how it works in Android..
        new Thread(new Runnable() {
            @Override
            public void run() {
                audioManager = (AudioManager) context.getApplicationContext().getSystemService(Context.AUDIO_SERVICE);
                mHandler.post(new Runnable() {
                    @Override
                    public void run() {
                        if(audioManager.getRingerMode() == AudioManager.RINGER_MODE_SILENT) {
                            audioManager.setRingerMode(AudioManager.RINGER_MODE_NORMAL);
                            Toast.makeText(context, "Ringer Mode set to Normal", Toast.LENGTH_SHORT).show();
                        } else {
                            audioManager.setRingerMode(AudioManager.RINGER_MODE_SILENT);
                            Toast.makeText(context, "Ringer Mode set to Silent", Toast.LENGTH_SHORT).show();
                        }
                    }
                });
            }
        }).start();

    }

}

我是一个Android新手,但这里是我根据以上答案创建的计时器类。它适用于我的应用程序,但我欢迎任何建议。

使用实例:

...{
public Handler uiHandler = new Handler();

  private Runnable runMethod = new Runnable()
    {
        public void run()
        {
              // do something
        }
    };

    timer = new UITimer(handler, runMethod, timeoutSeconds*1000);       
        timer.start();
}...

public class UITimer
{
    private Handler handler;
    private Runnable runMethod;
    private int intervalMs;
    private boolean enabled = false;
    private boolean oneTime = false;

    public UITimer(Handler handler, Runnable runMethod, int intervalMs)
    {
        this.handler = handler;
        this.runMethod = runMethod;
        this.intervalMs = intervalMs;
    }

    public UITimer(Handler handler, Runnable runMethod, int intervalMs, boolean oneTime)
    {
        this(handler, runMethod, intervalMs);
        this.oneTime = oneTime;
    }

    public void start()
    {
        if (enabled)
            return;

        if (intervalMs < 1)
        {
            Log.e("timer start", "Invalid interval:" + intervalMs);
            return;
        }

        enabled = true;
        handler.postDelayed(timer_tick, intervalMs);        
    }

    public void stop()
    {
        if (!enabled)
            return;

        enabled = false;
        handler.removeCallbacks(runMethod);
        handler.removeCallbacks(timer_tick);
    }

    public boolean isEnabled()
    {
        return enabled;
    }

    private Runnable timer_tick = new Runnable()
    {
        public void run()
        {
            if (!enabled)
                return;

            handler.post(runMethod);

            if (oneTime)
            {
                enabled = false;
                return;
            }

            handler.postDelayed(timer_tick, intervalMs);
        }
    }; 
}

我正在使用一个处理程序和可运行的来创建计时器。我将它包装在抽象类中。只需派生/实现它,您就可以开始了:

 public static abstract class SimpleTimer {
    abstract void onTimer();

    private Runnable runnableCode = null;
    private Handler handler = new Handler();

    void startDelayed(final int intervalMS, int delayMS) {
        runnableCode = new Runnable() {
            @Override
            public void run() {
                handler.postDelayed(runnableCode, intervalMS);
                onTimer();
            }
        };
        handler.postDelayed(runnableCode, delayMS);
    }

    void start(final int intervalMS) {
        startDelayed(intervalMS, 0);
    }

    void stop() {
        handler.removeCallbacks(runnableCode);
    }
}

请注意 handler.postDelayed 在要执行的代码之前调用-这将使计时器更加按“预期”关闭。但是,在某些情况下,计时器经常运行到( onTimer() )很长-可能有重叠。如果你想开始计数 intervalMS 任务完成后,移动 OnTimeR() 打电话到上面。

我相信在Android上这样做的方法是你需要一个后台服务来运行。在后台应用程序中,创建计时器。当计时器“滴答”时(设置等待时间间隔),启动要启动的活动。

http://developer.android.com/guide/topics/fundamentals.html (<--本文解释了Android开发的活动、服务、意图和其他核心基础之间的关系)

我过去经常使用( Timer , TimerTask )以及 Handler 定期启动(耗时的)任务。现在我已经将整个系统切换到了RxJava。RXJava提供 Observable.timer 它更简单,不易出错,使用方便。

public class BetterTimerFragment extends Fragment {
  public static final String TAG = "BetterTimer";
  private TextView timeView;
  private Subscription timerSubscription;

  @Override
  public View onCreateView(LayoutInflater inflater,
                           @Nullable ViewGroup container,
                           @Nullable Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_timer, container, false);
  }

  @Override
  public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    timeView = (TextView) view.findViewById(R.id.timeView);
  }

  @Override
  public void onResume() {
    super.onResume();

    // Right after the app is visible to users, delay 2 seconds
    // then kick off a (heavy) task every 10 seconds.
    timerSubscription = Observable.timer(2, 10, TimeUnit.SECONDS)
        .map(new Func1<Long, String>() {
          @Override
          public String call(Long unused) {
            // TODO: Probably do time-consuming work here.
            // This runs on a different thread than the main thread.
            return "Time: " + System.currentTimeMillis();
          }
        })
        .observeOn(AndroidSchedulers.mainThread())
        .subscribe(new Action1<String>() {
          @Override
          public void call(String timeText) {
            // The result will then be propagated back to the main thread.
            timeView.setText(timeText);
          }
        }, new Action1<Throwable>() {
          @Override
          public void call(Throwable throwable) {
            Log.e(TAG, throwable.getMessage(), throwable);
          }
        });
  }

  @Override
  public void onPause() {
    super.onPause();

    // Don't kick off tasks when the app gets invisible.
    timerSubscription.unsubscribe();
  }
}

对于定时操作,应使用 Handler .

如果您需要运行后台服务,那么AlarmManager就是您的选择。