Showing only one DialogFragment

Question

I am trying to set up a dialog fragment that pops up when my android user receives a push notification. The code I have below triggers the dialog. The issue I am running into is that if my users get multiple pushes, they will see multiple dialog boxes popup.

My desired action is to show only one dialog box and if another one pops up before the current one is closed, the current one should be destroyed and then the new one shown.

public abstract class BaseActivity extends ActionBarActivity {
  public void showShiftsDialog(String time) {
      String DIALOG_ALERT = "dialog_alert";

      FragmentTransaction transaction = getFragmentManager().beginTransaction();
      android.app.Fragment prev = getFragmentManager().findFragmentByTag(DIALOG_ALERT);

      if (prev != null) transaction.remove(prev);
      transaction.addToBackStack(null);

      // create and show the dialog
      DialogFragment newFragment = ShiftsDialogFragment.newInstance(time);
      newFragment.show(getSupportFragmentManager().beginTransaction(), DIALOG_ALERT);
  }
}

I have tried using the code from the android docs (http://developer.android.com/reference/android/app/DialogFragment.html). When debugging, it looks like prev is always null.

From my understanding, it looks like I am attaching the DialogFragment to the SupportFragmentManager:

newFragment.show(getSupportFragmentManager().beginTransaction(), DIALOG_ALERT);

and when I try to check to see if there are any current DialogFragment, I am checking from the FragmentManager:

 android.app.Fragment prev = getFragmentManager().findFragmentByTag(DIALOG_ALERT);

If I try to change the code to try to get it from the SupportFragmentManager, I get an incompatible type error where it is expecting android.app.Fragment, but I am returning a android.support.v4.app.Fragment:

android.app.Fragment prev = getSupportFragmentManager().findFragmentByTag(DIALOG_ALERT);

How can I manage my DialogFragment so that only one is shown at any given time?

Working Solution

public void showShiftsDialog(String time) {
    String DIALOG_ALERT = "dialog_alert";

    android.support.v4.app.FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    android.support.v4.app.Fragment prev = getSupportFragmentManager().findFragmentByTag(DIALOG_ALERT);

    if (prev != null){
        DialogFragment df = (DialogFragment) prev;
        df.dismiss();
        transaction.remove(prev);
    }

    transaction.addToBackStack(null);

    // create and show the dialog
    DialogFragment newFragment = ShiftsDialogFragment.newInstance(time);
    newFragment.show(getSupportFragmentManager().beginTransaction(), DIALOG_ALERT);
}

Answer 1

Your issue seems to be the incompatibility of the DialogFragment. If ShiftsDialogFragment is a sub-class of android.support.v4.app.DialogFragment you can use

android.support.v4.app.Fragment prev = getSupportFragmentManager().findFragmentByTag(DIALOG_ALERT);