CODEWITHSUNDEEP
androidandroid-preferences
Ifor
Ifor

Reputation: 2835

How to start preferenceActivity part way down the hierarchy

I am working at API level 9 so can not use the new Preference Fragment stuff.

I have a preference activity getting the preferences from and xml file as per the api demos. I have a hierarchy of preference screens so normaly to get to a preference you have to click though a top level screen.

As well as getting to all the preferences from my main menu I would like to be able to start the preference activity at one of the sub screens rather than the top screen so I can start it directly in one of the sub screens on say a click in an activity that that group of sub preferences is relervant to.

Anyone know if this is posible? I would of thought that passing some data with the intent would be the way but I can not find anything saying this is possible.

Upvotes: 0

Views: 2945

Answers (2)

Ifor
Ifor

Reputation: 2835

OK here is what I have ended up with with Kurtis's help.

Basically in my code starting the Preferences activity I have no action for all the preferences and an action if you want just some of them. The action needs to match the key on a preference or preferenceGroupe of some sort.

// all preferences
Intent launchPreferencesIntent = new Intent().setClass(this,
    PreferencesFromXml.class);
startActivity(launchPreferencesIntent);

// just key_trip_plot_control_preferences
Intent launchPreferencesIntent = new Intent(
    getString(R.string.key_trip_plot_control_preferences))
    .setClass(this, PreferencesFromXml.class);
startActivity(launchPreferencesIntent);

In my PreferencesFromXml class I always add the preferences from the xml but then if I have an action I search though the preferences looking for a matching key. If I find one I removeAll preferences then add the matching one or it's children if it is a PreferenceGroupe back in.

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.preferences);
    String act = getIntent().getAction();

    if (act != null) {
        Preference res = findPreferenceByKey(getPreferenceScreen(), act);
        if (res != null) {
            getPreferenceScreen().removeAll();
            if (res instanceof PreferenceGroup) {
                PreferenceGroup groupe = (PreferenceGroup) res;
                // add sub items
                for (int i = 0; i < groupe.getPreferenceCount(); i++) {
                    Preference pref = groupe.getPreference(i);
                    if (pref != null) {
                        getPreferenceScreen().addPreference(pref);
                    }
                }
            } else { // just add the item.
                getPreferenceScreen().addPreference(res);
            }
        }
    }
}

protected Preference findPreferenceByKey(PreferenceGroup in, String key) {
    for (int i = 0; i < in.getPreferenceCount(); i++) {
        Preference pref = in.getPreference(i);
        if (pref == null) {
            // should not happen
            Log.v(TAG, "findPreferenceByKey null pref i:" + i);
            return null;
        } else if (pref.hasKey() && pref.getKey().equals(key)) {
            return pref;
        } else if (pref instanceof PreferenceGroup) {
            // recurse
            Preference res = findPreferenceByKey((PreferenceGroup) pref,
                    key);
            if (res != null) {
                return res;
            }
        }
    }
    return null;
}

Upvotes: 1

Kurtis Nusbaum
Kurtis Nusbaum

Reputation: 30825

First of all, the Preference Fragment is available to you through the android compatibility package: http://developer.android.com/sdk/compatibility-library.html

Second, yes this is possible. When you're creating your fragment or acitvity (which ever you decide), use the addPreferencesFromIntent() method ( http://developer.android.com/reference/android/preference/PreferenceFragment.html#addPreferencesFromIntent%28android.content.Intent%29 ), and instead of adding the whole screen just add the subscreen you want.

Upvotes: 0

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