CODEWITHSUNDEEP
androidtimertimertask
user3675605
user3675605

Reputation: 39

NULL pointer exception on timer task

what i have is an image view and i have three pictures and i want the image to be changed automatically every 3 seconds , and i have used timer task to do this and here is my code:

public class MainActivity extends Activity {
    private ImageView frame;
    private int[] images = {R.drawable.boz_43, R.drawable.boz_42, R.drawable.boz_44};
    Timer timer;
    int i=0;
     private TimerTask updateTask;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        frame = (ImageView)findViewById(R.id.imageView1);
         timer = new Timer("TweetCollectorTimer");
         timer.schedule(updateTask, 6000L, 3000L);

         updateTask = new TimerTask() {

             @Override
             public void run() {

                MainActivity.this.runOnUiThread(new Runnable() {

                     @Override
                     public void run() { // TODO Auto-generated method stub
                         frame.setImageResource(images[i]);
                         i++;
                         if (i > 3)
                         {
                             i = 0;
                         }//if
                     }//run

                 });//runnable
             }
         };//timer task
    }
}

but each time i run my code i face a crash and it gives me a fatal exception : it says :

FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.androidanim/com.example.androidanim.MainActivity}: java.lang.NullPointerException
Caused by: java.lang.NullPointerException
at java.util.Timer.scheduleImpl(Timer.java:570)
at java.util.Timer.schedule(Timer.java:481)
at com.example.androidanim.MainActivity.onCreate(MainActivity.java:26)

and 26 line is :

timer.schedule(updateTask, 6000L, 3000L);

can you help me please???

Upvotes: 0

Views: 3542

Answers (2)

Giru Bhai
Giru Bhai

Reputation: 14408

Your updateTask is null.So use timer.schedule(updateTask, 6000L, 3000L); after initiating updateTask

So use onCreate as

   protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        frame = (ImageView)findViewById(R.id.imageView1);
         timer = new Timer("TweetCollectorTimer");


         updateTask = new TimerTask() {

             @Override
             public void run() {

                MainActivity.this.runOnUiThread(new Runnable() {

                     @Override
                     public void run() { // TODO Auto-generated method stub
                         frame.setImageResource(images[i]);
                         i++;
                         if (i > 3)
                         {
                             i = 0;
                         }//if
                     }//run

                 });//runnable
             }
         };//timer task
          timer.schedule(updateTask, 6000L, 3000L);
    }

Upvotes: 0

fedepaol
fedepaol

Reputation: 6862

You are using updateTask before creating it. Just call 

timer.schedule(updateTask, 6000L, 3000L);

after 

 updateTask = new TimerTask() { ..

Upvotes: 2

Related Questions