How to navigate to nested PreferencesScreen

Question

in my app I have nested PreferencesScreen's

<PreferencesScreen>
    <PreferencesScreen android:key="application">

    </PreferencesScreen>
</PreferencesScreen>

Now I want to fire Intent to take me from currrent Activity directly to application preferences subscreen. How can I do this?

Answer 1

In my application I have the similar task to show second-level PreferencesScreen programmatically. What I did:

1. In preferences.xml I assigned a key to PreferencesScreen I want to show (as shown in the question).

2. To show PreferencesScreen I wrote:

   final Intent preferencesActivity = new Intent(getBaseContext(), MyPreferencesActivity.class);
   preferencesActivity.putExtra("PREFERENCE_SCREEN_KEY", "key_of_preference_screen_to_show");
   startActivity(preferencesActivity);
   

3. Then in my PreferenceActivity class in method onCreate the following code was added:

   final Intent intent = getIntent();
   final String startScreen = intent.getStringExtra("PREFERENCE_SCREEN_KEY");
   if (startScreen != null) {
       getIntent().removeExtra("PREFERENCE_SCREEN_KEY");
       final Preference preference = findPreference(startScreen);
       final PreferenceScreen preferenceScreen = getPreferenceScreen();
       final ListAdapter listAdapter = preferenceScreen.getRootAdapter();
       final int itemsCount = listAdapter.getCount();
       int itemNumber;
       for (itemNumber = 0; itemNumber < itemsCount; ++itemNumber) {
           if (listAdapter.getItem(itemNumber).equals(preference)) {
               preferenceScreen.onItemClick(null, null, itemNumber, 0);
               break;
           }
       }
   }
   

One remark... Not only second-level PreferencesScreen, but the whole preferences hierarchy was loaded here. So, if you press Back button, the first (parent) PreferencesScreen will appear. In my case that was exactly what I needed. Not sure about yours.

Answer 2

Here is a way of handling the problem by grabbing the child-screen up front:

public class MyChildPreferenceActivity extends PreferenceActivity {

    private String screenKey = "myChildScreenKey";

    @Override
    public PreferenceScreen getPreferenceScreen() {
        PreferenceScreen root = super.getPreferenceScreen();
        if (root != null) {
            PreferenceScreen match = findByKey(root, screenKey);
            if (match != null) {
                return match;
            } else {
                throw new RuntimeException("key " + screenKey + " not found");
            }
        } else {
            return null;
        }
    }

    private PreferenceScreen findByKey(PreferenceScreen parent, String key) {
        if (key.equals(parent.getKey())) {
            return parent;
        } else {
            for (int i = 0; i < parent.getPreferenceCount(); i++) {
                Preference child = parent.getPreference(i);
                if (child instanceof PreferenceScreen) {
                    PreferenceScreen match = findByKey((PreferenceScreen) child, key);
                    if (match != null) {
                        return match;
                    }
                }
            }
            return null;
        }
    }

    // ...