Count Down Timer

Android provide a android.os.CountDownTimer. By new a CountDownTimer object, and overriding the call-back function onTick() and onFinish(), you can implement a count down timer easily.

package com.exercise.CountDownTimer;

import android.app.Activity;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.widget.TextView;

public class AndroidCountDownTimerActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

final TextView myCounter = (TextView)findViewById(R.id.mycounter);
new CountDownTimer(30000, 1000) {

@Override
public void onFinish() {
// TODO Auto-generated method stub
myCounter.setText("Finished!");
}

@Override
public void onTick(long millisUntilFinished) {
// TODO Auto-generated method stub
myCounter.setText("Millisecond Until Finished: " + String.valueOf(millisUntilFinished));
}

}.start();
}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello" />
<TextView
android:id="@+id/mycounter"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />

</LinearLayout>