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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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