Calling Fragment method from Activity / Activity method from Fragment

gistfile1.java

/*
 * From fragment to activty:
 */
((YourActivityClassName)getActivity()).yourPublicMethod();

/* 
 * From activity to fragment:
 */
FragmentManager fm = getSupportFragmentManager();
//if you added fragment via layout xml
YourFragmentClass fragment = (YourFragmentClass)fm.findFragmentById(R.id.your_fragment_id);
fragment.yourPublicMethod();
//If you added fragment via code and used a tag string when you added your fragment, use findFragmentByTag instead:
YourFragmentClass fragment = (YourFragmentClass)fm.findFragmentByTag("yourTag");

/*
 * Better approach:
 * Define an interface in the fragment, implement it in the activity
 * Call it from the fragment
 */
public class MyFragment {
  private MyStringListener listener;
  @Override
  public void onAttach(Activity activity) {
    super.onAttach(activity);
    try {
      listener = (MyStringListener) activity;
    } catch (ClassCastException castException) {
      /** The activity does not implement the listener. */
    }
  }
  public interface MyStringListener{
    public Integer computeSomething(String myString);
  }
}

 public class MyActivity extends FragmentActivity implements MyStringListener{
  @Override
  public Integer computeSomething(String myString){
   /** Do something with the string and return your Integer instead of 0 **/ 
   return 0;
  }
}

it returns null on the object

me too,

mee too