Android: CountDownTimer skips last onTick()!

Question

Code:

public class SMH extends Activity {  

    public void onCreate(Bundle b) {  
        super.onCreate(b);  
        setContentView(R.layou         


        

Answer 1

I also faced the same issue with CountDownTimer and I tried different approaches. So one of the easiest ways is in solution provided by @Nantoca - he suggests to double the frequency from 1000ms to 500ms. But I don't like this solution because it makes more work which will consume some extra battery resource.

So I decided to use @ocanal's soultion and to write my own simple CustomCountDownTimer.

But I found couple of flaws in his code:

1. It's a bit inefficient (creating second handler to publish results)

2. It starts to publish first result with a delay. (You need to do a post() method rather than postDelayed() during first initialization)

3. odd looking. Methods with capital letter, status instead of classic isCanceled boolean and some other.

So I cleaned it a bit and here is the more common version of his approach:

private class CustomCountDownTimer {

    private Handler mHandler;
    private long millisUntilFinished;
    private long countDownInterval;
    private boolean isCanceled = false;

    public CustomCountDownTimer(long millisUntilFinished, long countDownInterval) {
        this.millisUntilFinished = millisUntilFinished;
        this.countDownInterval = countDownInterval;
        mHandler = new Handler();
    }

    public synchronized void cancel() {
        isCanceled = true;
        mHandler.removeCallbacksAndMessages(null);
    }

    public long getRemainingTime() {
        return millisUntilFinished;
    }

    public void start() {

        final Runnable counter = new Runnable() {

            public void run() {

                if (isCanceled) {
                    publishUpdate(0);
                } else {

                    //time is out
                    if(millisUntilFinished <= 0){
                        publishUpdate(0);
                        return;
                    }

                    //update UI:
                    publishUpdate(millisUntilFinished);

                    millisUntilFinished -= countDownInterval;
                    mHandler.postDelayed(this, countDownInterval);
                }
            }
        };

        mHandler.post(counter);
    }
}

Answer 2

I don't know why the last tick is not working but you can create your own timer with Runable , for example.

class MyCountDownTimer {
    private long millisInFuture;
    private long countDownInterval;
    public MyCountDownTimer(long pMillisInFuture, long pCountDownInterval) {
            this.millisInFuture = pMillisInFuture;
            this.countDownInterval = pCountDownInterval;
        }
    public void Start() 
    {
        final Handler handler = new Handler();
        Log.v("status", "starting");
        final Runnable counter = new Runnable(){

            public void run(){
                if(millisInFuture <= 0) {
                    Log.v("status", "done");
                } else {
                    long sec = millisInFuture/1000;
                    Log.v("status", Long.toString(sec) + " seconds remain");
                    millisInFuture -= countDownInterval;
                    handler.postDelayed(this, countDownInterval);
                }
            }
        };

        handler.postDelayed(counter, countDownInterval);
    }
}

and to start it,

new MyCountDownTimer(10000, 2000).Start();

---

EDIT FOR GOOFY'S QUESTION

you should have a variable to hold counter status (boolean) . then you can write a Stop() method like Start().

EDIT-2 FOR GOOFY'S QUESTION

actually there is no bug on stopping counter but there is a bug on start again after stop(resume).

I'm writing a new updated full code that I had just tried and it's working. It's a basic counter that show time on screen with start and stop button.

class for counter

public class MyCountDownTimer {
    private long millisInFuture;
    private long countDownInterval;
    private boolean status;
    public MyCountDownTimer(long pMillisInFuture, long pCountDownInterval) {
            this.millisInFuture = pMillisInFuture;
            this.countDownInterval = pCountDownInterval;
            status = false;
            Initialize();
    }

    public void Stop() {
        status = false;
    }

    public long getCurrentTime() {
        return millisInFuture;
    }

    public void Start() {
        status = true;
    }
    public void Initialize() 
    {
        final Handler handler = new Handler();
        Log.v("status", "starting");
        final Runnable counter = new Runnable(){

            public void run(){
                long sec = millisInFuture/1000;
                if(status) {
                    if(millisInFuture <= 0) {
                        Log.v("status", "done");
                    } else {
                        Log.v("status", Long.toString(sec) + " seconds remain");
                        millisInFuture -= countDownInterval;
                        handler.postDelayed(this, countDownInterval);
                    }
                } else {
                    Log.v("status", Long.toString(sec) + " seconds remain and timer has stopped!");
                    handler.postDelayed(this, countDownInterval);
                }
            }
        };

        handler.postDelayed(counter, countDownInterval);
    }
}

activity class

public class CounterActivity extends Activity {
    /** Called when the activity is first created. */
    TextView timeText;
    Button startBut;
    Button stopBut;
    MyCountDownTimer mycounter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        timeText = (TextView) findViewById(R.id.time);
        startBut = (Button) findViewById(R.id.start);
        stopBut = (Button) findViewById(R.id.stop);
        mycounter = new MyCountDownTimer(20000, 1000);
        RefreshTimer();
    }

    public void StartTimer(View v) {
        Log.v("startbutton", "saymaya basladi");
        mycounter.Start();
    }

    public void StopTimer(View v) {
        Log.v("stopbutton", "durdu");
        mycounter.Stop();
    }

    public void RefreshTimer() 
    {
        final Handler handler = new Handler();
        final Runnable counter = new Runnable(){

            public void run(){
                timeText.setText(Long.toString(mycounter.getCurrentTime()));
                handler.postDelayed(this, 100);
            }
        };

        handler.postDelayed(counter, 100);
    }
}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:weightSum="1">
    <TextView android:textAppearance="?android:attr/textAppearanceLarge" 
              android:text="TextView" android:layout_height="wrap_content" 
              android:layout_width="wrap_content" 
              android:id="@+id/time">
    </TextView>
    <Button android:text="Start" 
            android:id="@+id/start" 
            android:layout_width="wrap_content" 
            android:layout_height="wrap_content" 
            android:onClick="StartTimer">
    </Button>
    <Button android:text="Stop" 
            android:id="@+id/stop" 
            android:layout_width="wrap_content" 
            android:layout_height="wrap_content" 
            android:onClick="StopTimer">
    </Button>
</LinearLayout>

Answer 3

So I think I went a little over board because my timer runs in its own thread instead of using postDelay handlers, though it always posts back to the thread it was created in. I also knew that I only cared about seconds so its simplified around that idea. It also lets you cancel it and restart it. I do not have pausing built in because that's not in my needs.

/**
* Created by MinceMan on 8/2/2014.
*/
public abstract class SecondCountDownTimer {

private final int seconds;
private TimerThread timer;
private final Handler handler;

/**
 * @param secondsToCountDown Total time in seconds you wish this timer to count down.
 */
public SecondCountDownTimer(int secondsToCountDown) {
    seconds = secondsToCountDown;
    handler = new Handler();
    timer = new TimerThread(secondsToCountDown);
}

/** This will cancel your current timer and start a new one.
 *  This call will override your timer duration only one time. **/
public SecondCountDownTimer start(int secondsToCountDown) {
    if (timer.getState() != State.NEW) {
        timer.interrupt();
        timer = new TimerThread(secondsToCountDown);
    }
    timer.start();
    return this;
}

/** This will cancel your current timer and start a new one. **/
public SecondCountDownTimer start() {
    return start(seconds);
}

public void cancel() {
    if (timer.isAlive()) timer.interrupt();
    timer = new TimerThread(seconds);
}

public abstract void onTick(int secondsUntilFinished);
private Runnable getOnTickRunnable(final int second) {
    return new Runnable() {
        @Override
        public void run() {
            onTick(second);
        }
    };
}

public abstract void onFinish();
private Runnable getFinishedRunnable() {
    return new Runnable() {
        @Override
        public void run() {
            onFinish();
        }
    };
}

private class TimerThread extends Thread {

    private int count;

    private TimerThread(int count) {
        this.count = count;
    }

    @Override
    public void run() {
        try {
            while (count != 0) {
                handler.post(getOnTickRunnable(count--));
                sleep(1000);
            }
        } catch (InterruptedException e) { }
        if (!isInterrupted()) {
            handler.post(getFinishedRunnable());
        }
    }
}

}

Answer 4

You are calculating time remaining incorrectly. The callback gets the number of milliseconds until completion of the task.

public void onTick(long m) {  
    long sec = m/1000+1;  
    tv.append(sec+" seconds remain\n");  
}  

should be

public void onTick(long m) {  
    long sec = m/1000;  
    tv.append(sec+" seconds remain\n");  
}

I've never used this class myself but it looks like you will not get a callback the instant it starts, which is why it appears like you're missing an entry. e.g. 10000 ms, 1000 ms per tick you'd get a total of 9 update callbacks, not 10 - 9000, 8000, 7000, 6000, 5000, 4000, 3000, 2000, 1000, finish.

Answer 5

Add a few milliseconds to your timer to allow it time to process the code. I added +100 to your timer-length, and also Math.ceil() to round up the result, rather than adding 1.

Also... the first tick is AFTER 2000 millis, so you won't get a "10 seconds left" entry unless you add it.

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    final TextView tv = (TextView) findViewById(R.id.tv);
    tv.setText("10 Seconds remain\n"); //displayed before the first tick.
    new CountDownTimer(10000+25, 1000) { //25 to account for processing time
        public void onTick(long m) {
            long sec = (long) Math.ceil(m / 2000 ); //round up, don't add 1
            tv.append(sec + " seconds remain\n");
        }
        public void onFinish() {
            tv.append("Done!");
        }
    }.start();
}

Answer 6

The most simple solution I came up with is as follows. Note that it only works if you need a simple screen to display with a seconds countdown.

mTimer = new CountDownTimer(5000, 100){
            public void onTick(long millisUntilFinished) {
                mTimerView.setText(Long.toString(millisUntilFinished/1000));                
             }

             public void onFinish() {
                 mTimerView.setText("Expired");
             }
        };

        mTimer.start();

In the code above the onTick() is called every 100 milliseconds but visually only seconds are displayed.