Couldn't reposition views programatically in an Activity android

Question

I have 5 buttons in an Activity with relative layout. I have a function called init() which will reposition the buttons using setX() and setY(). When I call init() from inside the onClickListener, the buttons are rearranged without any problem. But when I call the function from onCreate() or onStart(), the log shows that the function has been executed but the buttons stays in same position. What should I do?

Also If I call init() from onResume(), the buttons are repositioned without problem.

public class MainActivity extends ActionBarActivity {
@Override
protected void onStart()
{
    super.onStart();
}
@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    //if init() is called here I can see the Log "Tag/Init Executed" but the buttons are not repositioned
}
@Override
protected void onResume()
{
    Log.i("Log", "resume called");
    super.onResume();
    //if i call init() here, the button is not repositioned but if i click home button and resume the app again, the button is repositioned.
}
public void init()
{
    Log.i("Tag","Init Executed");
    b1=(ImageButton)findViewById(R.id.imageButton);
    b1.setX(p.x);
    b1.setY(p.y);
}
}

Answer 1

Okay, I solved this, long time ago. Just now got time to update it. It worked for me after using this.

View myView=view.findViewById(R.id.parent);
myView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {
         init();
    }

Answer 2

onCreate():

Called when the activity is first created. This is where you should do all of your normal static set up: create views, bind data to lists, etc. This method also provides you with a Bundle containing the activity's previously frozen state, if there was one. Always followed by onStart().

onRestart():

Called after your activity has been stopped, prior to it being started again. Always followed by onStart()

onStart():

Called when the activity is becoming visible to the user. Followed by onResume() if the activity comes to the foreground, or onStop() if it becomes hidden.

Android activity life cycle - what are all these methods for?