Access parent activity's method from dialog

Access parent activity's method from dialog

My project have a activity named MainActivity and a BrowserActivity extend
dialog service.
MainActivity will intent BrowserActivity on application started.
I would like to BrowserActivity can access MainActivity's public method.
something like that: Method on MainActivity:
public void chooseShare(Intent intent)
{
try
{
startActivityForResult( intent , PICK_SHARE);
} catch (android.content.ActivityNotFoundException ex)
{
Log.e("Share" , ex.getMessage());
}
}
And i want to do on BrowserActivity : (Pseudocode)
((MainActivity)BrowserActivity.this.getOwnerActivity()).chooseShare(intent);
I try to do that:
MainActivity ma = new MainActivity();
ma.chooseShare(i);
However, it not work, it throw NULLPointerException.
Because i need startActivityForResult() instead of startActivity() for
callback result. And i digg on SOF, i found startActivityForResult()
should be start on Activiy, but not Dialog. thanks you.