Dynamic ListPreference in android

问题:

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?

回答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);

回答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"};

回答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: