Tuesday, December 3, 2013

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.

Example of using Timer and TimerTask


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>


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6 comments:

Marcin Tab said...

Thanks fot the info, was looking for it for quite a while.

Anonymous said...

Really helpfull thanks!!!

Abdul Basit said...

i have question that when i press back button or activity destroys the timer still works which is good but when i again start application the new timer will create and the previous timer will also be in a running state. how to fix this problem.

Anonymous said...

Abdul, try canceling the timer con the screen's onPause

Shriyanshu Jain said...

Nice example.

Anonymous said...

Its not updating in real time.