倒计时

布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:orientation="vertical"
    android:layout_height="match_parent"
    tools:context="com.jikexueyuan.counttime.MainActivity" >




    <EditText
        android:id="@+id/inputtime"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:ems="10" >
        <requestFocus />
    </EditText>
    
    <Button
        android:id="@+id/gettime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="获取倒计时时间" />


    <TextView
        android:id="@+id/time"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />


    <Button
        android:id="@+id/starttime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="开始计时" />


    <Button
        android:id="@+id/stoptime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="停止计时" />

</LinearLayout>

Activity:

public class MainActivity extends Activity implements OnClickListener{

private EditText inputet;
private Button getTime,startTime,stopTime;
private TextView time;
private int i = 0;
private Timer timer = null;
private TimerTask task = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }
    
    private void initView(){
     inputet = (EditText) findViewById(R.id.inputtime);
        getTime = (Button) findViewById(R.id.gettime);
        startTime = (Button) findViewById(R.id.starttime);
        stopTime = (Button) findViewById(R.id.stoptime);
        time = (TextView) findViewById(R.id.time);
        getTime.setOnClickListener(this);
        startTime.setOnClickListener(this);
        stopTime.setOnClickListener(this);
    }


@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.gettime:
time.setText(inputet.getText().toString());
i = Integer.parseInt(inputet.getText().toString());
break;


case R.id.starttime:
startTime();
break;
case R.id.stoptime:
stopTime();
break;
}
}

private Handler mHandler = new Handler(){
public void handleMessage(Message msg) {
time.setText(msg.arg1+"");
startTime();
};
};

public void startTime(){
timer = new Timer();
task = new TimerTask() {

@Override
public void run() {
i--;
Message  message = mHandler.obtainMessage();
message.arg1 = i;
mHandler.sendMessage(message);
}
};
timer.schedule(task, 1000);
}

public void stopTime(){
timer.cancel();
}
    
}