public class ChronometerActivity extends Activity implements OnClickListener {  private Chronometer mChronometer;  private Button start, stop, reset, format, clear_format;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_chronometer);    // 初始化View widget    initViews();    // 設(shè)置監(jiān)聽(tīng)事件    initListeners();  }  private void initListeners() {    start.setOnClickListener(this);    stop.setOnClickListener(this);    reset.setOnClickListener(this);    format.setOnClickListener(this);    clear_format.setOnClickListener(this);  }  private void initViews() {    mChronometer = (Chronometer) findViewById(R.id.chronometer);    start = (Button) findViewById(R.id.start);    stop = (Button) findViewById(R.id.stop);    reset = (Button) findViewById(R.id.reset);    format = (Button) findViewById(R.id.set_format);    clear_format = (Button) findViewById(R.id.clear_format);  }  View.OnClickListener mStartListener = new OnClickListener() {    public void onClick(View v) {      mChronometer.start();    }  };  View.OnClickListener mStopListener = new OnClickListener() {    public void onClick(View v) {      mChronometer.stop();    }  };  View.OnClickListener mResetListener = new OnClickListener() {    public void onClick(View v) {      mChronometer.setBase(SystemClock.elapsedRealtime());    }  };  View.OnClickListener mSetFormatListener = new OnClickListener() {    public void onClick(View v) {      mChronometer.setFormat("Formatted time (%s)");    }  };  View.OnClickListener mClearFormatListener = new OnClickListener() {    public void onClick(View v) {      mChronometer.setFormat(null);    }  };  @Override  public void onClick(View v) {    switch (v.getId()) {    case R.id.start:      mChronometer.start();// 開(kāi)始計(jì)時(shí)      break;    case R.id.stop:      mChronometer.stop();// 暫停計(jì)時(shí)      break;    case R.id.reset:      mChronometer.setBase(SystemClock.elapsedRealtime());// 從開(kāi)機(jī)到現(xiàn)在的毫秒數(shù)      break;    case R.id.set_format:      // 需要一個(gè)String變量，并使用"%s"表示計(jì)時(shí)信息      mChronometer.setFormat("時(shí)間累計(jì):%s秒");      break;    case R.id.clear_format:      mChronometer.setFormat(null);      break;    }  }}

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  android:layout_width="match_parent"  android:layout_height="match_parent"  android:gravity="center_horizontal"  android:orientation="vertical"  android:padding="10dip" >  <Chronometer    android:id="@+id/chronometer"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:format="@string/chronometer_initial_format"    android:paddingBottom="30dip"    android:paddingTop="30dip"    android:textSize="15sp" />  <Button    android:id="@+id/start"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="開(kāi)始" >    <requestFocus />  </Button>  <Button    android:id="@+id/stop"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="暫停" >  </Button>  <Button    android:id="@+id/reset"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="重新計(jì)時(shí)" >  </Button>  <Button    android:id="@+id/set_format"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="信息說(shuō)明" >  </Button>  <Button    android:id="@+id/clear_format"    android:layout_width="wrap_content"    android:layout_height="wrap_content"    android:text="取消說(shuō)明" >  </Button></LinearLayout>