This is a sample application, we will create a countdown timer in android using the CountDownTimerclass .This is an example of showing a 30 second countdown in a TextView . We will update the TextView on every tick of the timer.The option to stop and restart the timer is also provided.

This is a sample application,  we will create a countdown timer in android using the CountDownTimerclass .This is an example of showing a 30 second countdown in a TextView . We will update the TextView on every tick of the timer.The option to stop and restart the timer is also provided.

So let us start:

1.Create a new project File ->New -> Project ->Android ->Android Application Project. While creating the new project, name the activity as TimerActivity(TimerActivity.java) and layout asactivity_timer.xml.

2.Now let us design the UI for the TimerActivity i.e activity_timer.xml with a textview and a button.

activity_timer.xml

01	<?xml version="1.0" encoding="utf-8"?>

02	<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

03	android:layout_width="fill_parent"

04	android:layout_height="fill_parent"

05	android:orientation="vertical"

06	android:background="@drawable/bgi" >

07

08

<TextView

09	android:id="@+id/timer"

10	android:layout_width="wrap_content"

11	android:layout_height="wrap_content"

12	android:layout_centerHorizontal="true"

13	android:layout_centerVertical="true"

14	android:paddingRight="10dip"

15	android:textSize="50dp" />

16

17

<Button

18	android:id="@+id/button"

19	android:layout_width="fill_parent"

20	android:layout_height="wrap_content"

21	android:layout_alignParentBottom="true"

22	android:layout_alignParentLeft="true"

23	android:text="Start" />

24

25	</RelativeLayout>

3.Now in the TimerActivity we implement the count down timer by extending the CountDownTimer class.Press Ctrl+Shift+O for missing imports after typing the code.

TimerActivity.java

01	public class TimerActivity extends Activity implements OnClickListener {

02

03	private CountDownTimer countDownTimer;

04	private boolean timerHasStarted = false;

05	private Button startB;

06	public TextView text;

07	private final long startTime = 30 * 1000;

08	private final long interval = 1 * 1000;

09

10

@Override

11	public void onCreate(Bundle savedInstanceState) {

12	super.onCreate(savedInstanceState);

13	setContentView(R.layout.activity_timer);

14	startB = (Button) this.findViewById(R.id.button);

15	startB.setOnClickListener(this);

16	text = (TextView) this.findViewById(R.id.timer);

17	countDownTimer = new MyCountDownTimer(startTime, interval);

18	text.setText(text.getText() + String.valueOf(startTime / 1000));

19

}

20

21

@Override

22	public void onClick(View v) {

23	if (!timerHasStarted) {

24	countDownTimer.start();

25	timerHasStarted = true;

26	startB.setText("STOP");

27

} else {

28	countDownTimer.cancel();

29	timerHasStarted = false;

30	startB.setText("RESTART");

31

}

32

}

33

34	public class MyCountDownTimer extends CountDownTimer {

35	public MyCountDownTimer(long startTime, long interval) {

36	super(startTime, interval);

37

}

38

39

@Override

40	public void onFinish() {

41	text.setText("Time's up!");

42

}

43

44

@Override

45	public void onTick(long millisUntilFinished) {

46	text.setText("" + millisUntilFinished / 1000);

47

}

48

}

49

50

}

4.Run the project by rightclicking project Run as → android project.

Output:

The output of this example would be similar to the one as follows: