Android：点击按钮时从另一个活动刷新/更新片段

Question

I have a Dialog prompt in mainActivity . If user close the Dialog, I need to show red dot to one of the ListView items inside fourthFragment (as per redbox in fourthFragment in image below).

The problem is the red dot only be updated after I close the app and reopened it, because fourthFragment already done created BEFORE user close the Dialog. How can I refresh/update the fourthFragment after Dialog closed so that red dot can be shown immediately?

short description:

• mainActivity : on Dialog closed > store showRedDot ="1" to local db
• fourthFragment : onCreate > read showRedDot from local db, if "1", show red dot. ( problem here, when onCreate, showRedDot is still "0", so I need to update fourthFragment layout after dialog closed.)

Answer 1

You have calling a interface to push event dismiss(button click) of dialog. Like this:

public interface MyDialogListener {
    void OnCloseDialog();
}

public class fourthFragment extend Fragment implements MyDialogListener {
    public void SomeMethod() {
        MyDialog myDialog = new MyDialog(this, this);
        myDialog.show();
    }

    public void OnCloseDialog() {
        // Do update your listview in here( maybe call method initialize data for listview)
    }

}

public class MyDialog extends Dialog {
    MyDialogListener mListener;

    public MyDialog (Context context, MyDialogListener listener) {
        super(context, R.style.Dialog);
        mListener = listener;
    }

    public void onClick(View view) {
        switch (view.getId()) {
            case R.id.CloseButton:
                // Push event when Dialog close(or anything)
                mListener.OnCloseDialog();
                dismiss()
                break;
            default:
                //...
        }
    }
}

Answer 2

Try Interface or Broadcast receivers as above. If else refresh the fragment as

    // Reload current fragment
Fragment frg = null;
frg = getSupportFragmentManager().findFragmentByTag("Your_Fragment_TAG");
final FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
ft.detach(frg);
ft.attach(frg);
ft.commit();