So I have basically two activities, and when I go back from the 2nd activity to the 1st activity, I want to change the transparency from the ImageButton in the 1st activity. How can I achieve this? (The code is from the 2nd activity)

```
public class StoreActivity extends Activity {

    ImageButton pokeb;

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.store_layout);
        pokeb = (ImageButton)findViewById(R.id.pokeball);
    }

    @Override
    public void onBackPressed() {
        super.onBackPressed();

        pokeb.setAlpha(1f);
    }
}

```