Question

i am designing a app for some quiz.
i need an activity that starts when i press the start button waits for 1 sec displays a red image,watis for 1 sec again displays a yellow face and waits for another sec and displays a green image.

The activity that starts when start quiz is pressed.

public class pgtwo extends Activity {

ImageView rface,yface,gface;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);

    setContentView(R.layout.newpg2);            


    rface = (ImageView) findViewById(R.id.imageView1);
    yface = (ImageView) findViewById(R.id.imageView2);
    gface = (ImageView) findViewById(R.id.imageView3);
    rface.setVisibility(ImageView.INVISIBLE);
    yface.setVisibility(ImageView.INVISIBLE);
    gface.setVisibility(ImageView.INVISIBLE);



           Thread trd = new Thread(){           
        @Override
        public void run() {
            // TODO Auto-generated method stub
            try {
                sleep(1000);
                rface.setVisibility(ImageView.VISIBLE);
                sleep(1000);
                yface.setVisibility(ImageView.VISIBLE);
                sleep(1000);
                gface.setVisibility(ImageView.VISIBLE);

            } catch (Exception e) {
                // TODO: handle exception
            }finally{
                Intent myIntent = new Intent("com.ak.qmttpack.pgthree");
                myIntent.putExtra("pname", pname);
                myIntent.putExtra("tabList", tabList);
                myIntent.putExtra("order",order);
                myIntent.putExtra("noq", noq);
                myIntent.putExtra("seq", seq);
                startActivity(myIntent);
            }
        }
    };
    trd.start();


}

}

i set the images visability as invisable and after waiting for 1 second each image visability becomes visable.
it waits for few seconds and starts the next activity.it dosent work as expected to. why any help plese.
or is there another way to get what i need.

Answer 1

You cannot modify the UI from your thread, and you are getting an Exception that you just ignore (which is very bad practice). To modify the UI from another thread you should either create a Handler inside the onCreate() method and then :

  handler.post(new Runnable() {
        @Override
        public void run() {
                  rface.setVisibility(View.Visible);        
        }
    });

or use runOnUiThread() from you thread.