1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:layout_width="fill_parent"
 4     android:layout_height="fill_parent"
 5     android:orientation="vertical" >
 6 
 7     <Chronometer
 8         android:id="@+id/chronometer1"
 9         android:layout_width="wrap_content"
10         android:layout_height="wrap_content"
11         android:text="Chronometer" />
12 
13     <Button
14         android:id="@+id/button1"
15         android:layout_width="wrap_content"
16         android:layout_height="wrap_content"
17         android:text="Start" />
18 
19 </LinearLayout>

 1 package android.demo;
 2 
 3 import android.app.Activity;
 4 import android.os.Bundle;
 5 import android.os.SystemClock;
 6 import android.view.View;
 7 import android.view.View.OnClickListener;
 8 import android.widget.Button;
 9 import android.widget.Chronometer;
10 import android.widget.Chronometer.OnChronometerTickListener;
11 
12 public class AndroidDemo5Activity extends Activity {
13     /** Called when the activity is first created. */
14     @Override
15     public void onCreate(Bundle savedInstanceState) {
16         super.onCreate(savedInstanceState);
17         setContentView(R.layout.main);
18 
19         Button start = (Button) findViewById(R.id.button1);
20         final Chronometer ch = (Chronometer) findViewById(R.id.chronometer1);
21 
22         start.setOnClickListener(new OnClickListener() {
23 
24             @Override
25             public void onClick(View arg0) {
26                 ch.setBase(SystemClock.elapsedRealtime());
27                 ch.start();
28             }
29         });
30         ch.setOnChronometerTickListener(new OnChronometerTickListener() {
31 
32             @Override
33             public void onChronometerTick(Chronometer arg0) {
34                 if (SystemClock.elapsedRealtime() - ch.getBase() > 20 * 1000) {
35                     ch.stop();
36                 }
37 
38             }
39         });
40     }
41 }