Dynamic ListPreference in android

Question

How to generate dynamic listPreference in android? I want to get all wifi access points and make a list using in preference Activity(i.e. make a list using listpreference). How to do this?

Sacroiliac

Considering that the items will be dynamic it is not enough to set the items in onCreate. You also need to update the values when the ListPreference is clicked: #6475207 – Linctus

Answer 1

Every XML element in Android can be created programmatically as the element name is also a Java class. Hence you can create a ListPreference in code:

CharSequence[] entries = { "One", "Two", "Three" };
CharSequence[] entryValues = { "1", "2", "3" };
ListPreference lp = new ListPreference(this);
lp.setEntries(entries);
lp.setEntryValues(entryValues);

You could alternatively create it in XML then add the entries/entry values in code:

CharSequence[] entries = { "One", "Two", "Three" };
CharSequence[] entryValues = { "1", "2", "3" };
ListPreference lp = (ListPreference)findPreference("list_key_as_defined_in_xml");
lp.setEntries(entries);
lp.setEntryValues(entryValues);

Oath

findViewById works with views. ListPreference isn't a view, so the second example doesn't seem to work. Can't cast. – Acidulent

findPreference should work instead of findViewById. However findPreference is deprecated in Honeycomb. – Calumniate

Answer 2

For creating a dynamic list preference, u need to create a preference activity (ie to extend an activity as PreferenceActivity).

The following code can be used to create the list dynamically.

// Root
        PreferenceScreen root = getPreferenceManager().createPreferenceScreen(this);
        dialogBasedPrefCat.setTitle("Category Title");
        root.addPreference(dialogBasedPrefCat); //Adding a category

 // List preference under the category
        ListPreference listPref = new ListPreference(this);
        listPref.setKey("keyName"); //Refer to get the pref value
        listPref.setEntries("Array of values");
        listPref.setEntryValues("Array of item value");
        listPref.setDialogTitle("Dialog Title"); 
        listPref.setTitle("Title");
        listPref.setSummary("Summary");
        dialogBasedPrefCat.addPreference(listPref); Adding under the category

        return root;

Hope this helps to get an !dea...

EDIT:

Create and add values to CharSequence[] like this:

CharSequence[] cs = new String[]{"myValue"};

Ophiuchus

See this example code for dynamically creating other kinds of preferences: developer.android.com/resources/samples/ApiDemos/src/com/… – Cilia

A little strange that getEntries and getEntryValues are DOA but I'm sure there's a good reason. And this is a great solution. – Noblenobleman

Boris - your link doesn't work: it just takes me to the Download Samples index. However, I followed the path indicated when hovering over your link in my downloaded samples and found it. (For anyone else: start from android-sdk\samples\android-<version>\ApiDemos then follow the rest of Boris's path) – Gilda

Samples path: sdk\samples\android-21\legacy\ApiDemos\src\com\example\android\apis\preference – Thorndike

Answer 3

This minimalist technique is for both environments.

In preferences.xml

<!-- NB: Dynamic array insertion for 'entries'/'entryValues' -->
<ListPreference
    android:key="xyzzy"
    android:title="..."
    android:summary="..."
    android:numeric="integer"
    android:defaultValue="0"
    android:layout="?PrefLayoutDtl" 
/>

In PreferenceFragment.onCreate()

addPreferencesFromResource(R.xml.preferences);
expand_xyzzy((ListPreference)findPreference("xyzzy"));

Elsewhere

public static Preference expand_xyzzy (ListPreference pref) {
    if (pref == null) return pref;
    pref.setEntries(new String["one","two","three];
    pref.setEntryValues(new String["0","1","2"]);
    return pref;
}

Notes:
(a) XML is self-documenting and perhaps a better choice than dynamic preference creation.
(b) Starting your PreferenceFragment by NOT using PreferenceActivity easily lets you do this:

Worldshaking