Example of using Timer and TimerTask on Android

Example of using Timer and TimerTask on Android

This exercise show how to use java.util.Timer and java.util.TimerTask in Android programming.

java.util.Timer is a facility for threads to schedule tasks for future execution in a background thread. Tasks may be scheduled for one-time execution, or for repeated execution at regular intervals. java.util.TimerTask is a task that can be scheduled for one-time or repeated execution by a Timer.

package com.example.androidtimer;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Timer;
import java.util.TimerTask;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.TextView;
import android.app.Activity;

public class MainActivity extends Activity {
 
 CheckBox optSingleShot;
 Button btnStart, btnCancel;
 TextView textCounter;
 
 Timer timer;
 MyTimerTask myTimerTask;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  optSingleShot = (CheckBox)findViewById(R.id.singleshot);
  btnStart = (Button)findViewById(R.id.start);
  btnCancel = (Button)findViewById(R.id.cancel);
  textCounter = (TextView)findViewById(R.id.counter);
  
  btnStart.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View arg0) {

    if(timer != null){
     timer.cancel();
    }
    
    //re-schedule timer here
    //otherwise, IllegalStateException of
    //"TimerTask is scheduled already" 
    //will be thrown
    timer = new Timer();
    myTimerTask = new MyTimerTask();
    
    if(optSingleShot.isChecked()){
     //singleshot delay 1000 ms
     timer.schedule(myTimerTask, 1000);
    }else{
     //delay 1000ms, repeat in 5000ms
     timer.schedule(myTimerTask, 1000, 5000);
    }
   }});
  
  btnCancel.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View v) {
    if (timer!=null){
     timer.cancel();
     timer = null;
    }
   }
  });
  
 }

 class MyTimerTask extends TimerTask {

  @Override
  public void run() {
   Calendar calendar = Calendar.getInstance();
   SimpleDateFormat simpleDateFormat = 
     new SimpleDateFormat("dd:MMMM:yyyy HH:mm:ss a");
   final String strDate = simpleDateFormat.format(calendar.getTime());
   
   runOnUiThread(new Runnable(){

    @Override
    public void run() {
     textCounter.setText(strDate);
    }});
  }
  
 }

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />
    <CheckBox 
        android:id="@+id/singleshot"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Single Shot"/>
 <Button 
     android:id="@+id/start"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Start"/>
 <Button 
     android:id="@+id/cancel"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Cancel"/>
    <TextView
     android:id="@+id/counter"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:textSize="30dp"
        android:textStyle="bold"/>
</LinearLayout>