Update existing Preference-item in a PreferenceActivity upon returning from a (sub)PreferenceScreen

Question

I have a PreferenceActivity with a bunch of (Sub)PreferenceScreens. Each such (Sub)PreferenceScreen represents an account and has the account-username as its title.

PreferenceScreen root = mgr.createPreferenceScreen(this);
for (MyAccountClass account : myAccounts) {
    final PreferenceScreen accScreen = mgr.createPreferenceScreen(this);

    accScreen.setTitle(account.getUsername());

    // add Preferences to the accScreen
    // (for instance a "change username"-preference)
    ...

    root.add(accScreen);
}

As the user enters sub-PreferenceScreen, and edits the account user-name, I want the outer PreferenceScreen to update it's PreferenceScreen-title for the account in question.

I've tried to add...

usernamePref.setOnPreferenceChangeListener(new OnPreferenceChangeListener() {
    public boolean onPreferenceChange(Preference preference, Object newValue) {
        accScreen.setTitle(newValue.toString());
        return true;
    }
});

...but the accScreen.setTitle does not seem to take effect on the outer PreferenceScreen. I've note that calling onContentChanged(); actually makes it work, but I realize that this is probably not the preferred way of doing it.

I suspect I should call postInvalidate() on some view somewhere, but I really can't figure out on what view and when to do it.

http://stackoverflow.com/questions/2396153/preferencescreen-androidsummary-update may be experiening the same problem as me.

Any help appreciated.

Answer 1

Experiencing this same problem, but onContentChanged() isn't working for me. My problem is with PreferenceScreens that are more than one level deep from the root.

To follow your example, if you first created an "Accounts" PreferenceScreen, and then added each of your individual account PreferenceScreen objects under that. Like this:

Root Screen
  -> "Accounts" screen
    -> "[email protected]" screen
      -> edit username
      -> edit password
      -> etc...
    -> "[email protected]" screen
    -> "[email protected]" screen
    -> etc...

If a user edited their username and clicked save, calling PreferenceActivity.onContentChanged() seems to only affect direct descendants of the root PreferenceScreen. The third-generation screens' titles and summaries do not get redrawn, still reflecting old values.

Looking through the code for onContentChanged(), it looks like it just re-bind()s the root Screen to the ListActivity's ListView, although I don't think subsequent PreferenceScreens are ever bound to a ListView (are they?), so we can't manually re-bind anything...

The only workaround I can think of would be to create the sub-menus as isolated PreferenceActivitys instead of PreferenceScreens, so we can intentionally call onContentChanged() on our direct ancestor. But that's even more of a kludge than the current workaround. Any ideas?