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MultiSelectListPreference example

I am having a hard time trying to find a good example of the MultiSelectListPreference provided in the Android API. I have seen many references to this blog, and tho this is the end result I desire, I don't want to create a class for each multi-select preference I want to implement.
Ultimately I want to see the preferences xml for a simple multi-select dialog (which i will populate the values for dynamically), as well to the call to addPreferencesFromResource(R.xml.preferences);

addPreferencesFromResource(R.xml.preferences);

Currently, I have:

<MultiSelectListPreference
android:defaultValue=""
android:enabled="true"
android:entries="@array/pref_default_entries"
android:entryValues="@array/pref_default_values"
android:key="TargetList"
android:persistent="true"
android:summary="@string/TargetSummary"
android:title="@string/TargetTitle" />


and when I try to call addPreferencesFromResource in my Activities onCreate call I am getting the following error:

06-18 13:59:30.690: E/AndroidRuntime(6052): FATAL EXCEPTION: main
06-18 13:59:30.690: E/AndroidRuntime(6052): java.lang.RuntimeException: Unable to start activity ComponentInfocom.tracker/com.tracker.TrackerActivity: android.view.InflateException: Binary XML file line #37: Error inflating class java.lang.reflect.Constructor
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1818)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1834)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.app.ActivityThread.access$500(ActivityThread.java:122)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1027)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.os.Handler.dispatchMessage(Handler.java:99)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.os.Looper.loop(Looper.java:132)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.app.ActivityThread.main(ActivityThread.java:4126)
06-18 13:59:30.690: E/AndroidRuntime(6052): at java.lang.reflect.Method.invokeNative(Native Method)
06-18 13:59:30.690: E/AndroidRuntime(6052): at java.lang.reflect.Method.invoke(Method.java:491)
06-18 13:59:30.690: E/AndroidRuntime(6052): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:844)
06-18 13:59:30.690: E/AndroidRuntime(6052): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602)
06-18 13:59:30.690: E/AndroidRuntime(6052): at dalvik.system.NativeStart.main(Native Method)
06-18 13:59:30.690: E/AndroidRuntime(6052): Caused by: android.view.InflateException: Binary XML file line #37: Error inflating class java.lang.reflect.Constructor
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.GenericInflater.createItem(GenericInflater.java:397)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.GenericInflater.onCreateItem(GenericInflater.java:417)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.GenericInflater.createItemFromTag(GenericInflater.java:428)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.GenericInflater.rInflate(GenericInflater.java:481)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.GenericInflater.inflate(GenericInflater.java:326)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.GenericInflater.inflate(GenericInflater.java:263)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:269)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.PreferenceActivity.addPreferencesFromResource(PreferenceActivity.java:1366)
06-18 13:59:30.690: E/AndroidRuntime(6052): at com.tracker.TrackerActivity.onCreate(TrackerActivity.java:30)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1050)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1782)
06-18 13:59:30.690: E/AndroidRuntime(6052): ... 11 more
06-18 13:59:30.690: E/AndroidRuntime(6052): Caused by: java.lang.reflect.InvocationTargetException
06-18 13:59:30.690: E/AndroidRuntime(6052): at java.lang.reflect.Constructor.constructNative(Native Method)
06-18 13:59:30.690: E/AndroidRuntime(6052): at java.lang.reflect.Constructor.newInstance(Constructor.java:416)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.GenericInflater.createItem(GenericInflater.java:383)
06-18 13:59:30.690: E/AndroidRuntime(6052): ... 21 more
06-18 13:59:30.690: E/AndroidRuntime(6052): Caused by: java.lang.NullPointerException
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.content.res.AssetManager.getResourceTextArray(AssetManager.java:215)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.content.res.Resources.getTextArray(Resources.java:435)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.content.res.TypedArray.getTextArray(TypedArray.java:628)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.MultiSelectListPreference.onGetDefaultValue(MultiSelectListPreference.java:210)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.Preference.<init>(Preference.java:257)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.DialogPreference.<init>(DialogPreference.java:69)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.DialogPreference.<init>(DialogPreference.java:90)
06-18 13:59:30.690: E/AndroidRuntime(6052): at android.preference.MultiSelectListPreference.<init>(MultiSelectListPreference.java:49)
06-18 13:59:30.690: E/AndroidRuntime(6052): ... 24 more


I look forward to your reply!

4 Answers
4

Sigrist is correct, to solve the initial error you are seeing. It needs default values provided, even if its empty. This helped me in that I want to provide values at RUNTIME, but not mess with the full implementation.

See this code for how I provide values at runtime, while not having to handle the full implementation.

public class CalendarListPreference extends MultiSelectListPreference

ContentResolver cr;
Cursor cursor;
String projection = new String CalendarContract.Calendars.NAME, CalendarContract.Calendars.CALENDAR_DISPLAY_NAME;
String selection = "(" + CalendarContract.Calendars.VISIBLE + " = ?)";
String selectionArgs = new String "1" ;

public CalendarListPreference(Context context, AttributeSet attrs)
super(context, attrs);

List<CharSequence> entries = new ArrayList<CharSequence>();
List<CharSequence> entriesValues = new ArrayList<CharSequence>();

cr = context.getContentResolver();
cursor = cr.query(CalendarContract.Calendars.CONTENT_URI, projection, selection, selectionArgs, null);

while (cursor.moveToNext())
String name = cursor.getString(0);
String displayName = cursor.getString(1);

entries.add(name);
entriesValues.add(displayName);


setEntries(entries.toArray(new CharSequence));
setEntryValues(entriesValues.toArray(new CharSequence));




In my strings.xml

<string-array name="pref_calendar_list_default">
</string-array>


In my preferences.xml

<com.mynameistodd.autovolume.CalendarListPreference
android:defaultValue="@array/pref_calendar_list_default"
android:key="@string/pref_calendar_list_key"
android:summary="@string/pref_calendar_list_summary"
android:title="@string/pref_calendar_list_title"
android:dependency="@string/pref_calendar_enabled_key"/>


I know this is a bit of an old question, but it helped me, so here is my answer!

You need to specify the defaultValues property

<MultiSelectListPreference
android:dialogTitle="@string/mode_repeat"
android:key="mode_repeat"
android:summary=""
android:title="@string/mode_repeat"
android:entries="@array/weekdays"
android:entryValues="@array/weekdays_values"
android:defaultValue="@array/empty_array"
/>


If you don't want default values, create an empty array in your strings.xml

<string-array name="empty_array"/>


I've created MultiSelectListPreference for devices running Android in the API earlier than level 11.

https://gist.github.com/cardil/4754571

package pl.wavesoftware.widget;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

import android.app.AlertDialog.Builder;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnMultiChoiceClickListener;
import android.content.res.TypedArray;
import android.preference.ListPreference;
import android.util.AttributeSet;

public class MultiSelectListPreference extends ListPreference

private String separator;
private static final String DEFAULT_SEPARATOR = "u0001u0007u001Du0007u0001";
private boolean entryChecked;

public MultiSelectListPreference(Context context, AttributeSet attributeSet)
super(context, attributeSet);
entryChecked = new boolean[getEntries().length];
separator = DEFAULT_SEPARATOR;


public MultiSelectListPreference(Context context)
this(context, null);


@Override
protected void onPrepareDialogBuilder(Builder builder)
CharSequence entries = getEntries();
CharSequence entryValues = getEntryValues();
if (entries == null

private CharSequence unpack(CharSequence val)
if (val == null

/**
* Gets the entries values that are selected
*
* @return the selected entries values
*/
public CharSequence getCheckedValues()
return unpack(getValue());


private void restoreCheckedEntries()
CharSequence entryValues = getEntryValues();

// Explode the string read in sharedpreferences
CharSequence vals = unpack(getValue());

if (vals != null)
List<CharSequence> valuesList = Arrays.asList(vals);
for (int i = 0; i < entryValues.length; i++)
CharSequence entry = entryValues[i];
entryChecked[i] = valuesList.contains(entry);




@Override
protected void onDialogClosed(boolean positiveResult)
List<CharSequence> values = new ArrayList<CharSequence>();

CharSequence entryValues = getEntryValues();
if (positiveResult && entryValues != null)
for (int i = 0; i < entryValues.length; i++)
if (entryChecked[i] == true)
String val = (String) entryValues[i];
values.add(val);



String value = join(values, separator);
setSummary(prepareSummary(values));
setValueAndEvent(value);



private void setValueAndEvent(String value)
if (callChangeListener(unpack(value)))
setValue(value);



private CharSequence prepareSummary(List<CharSequence> joined)
List<String> titles = new ArrayList<String>();
CharSequence entryTitle = getEntries();
CharSequence entryValues = getEntryValues();
int ix = 0;
for (CharSequence value : entryValues)
if (joined.contains(value))
titles.add((String) entryTitle[ix]);

ix += 1;

return join(titles, ", ");


@Override
protected Object onGetDefaultValue(TypedArray typedArray, int index)
return typedArray.getTextArray(index);


@Override
protected void onSetInitialValue(boolean restoreValue,
Object rawDefaultValue)
String value = null;
CharSequence defaultValue;
if (rawDefaultValue == null)
defaultValue = new CharSequence[0];
else
defaultValue = (CharSequence) rawDefaultValue;

List<CharSequence> joined = Arrays.asList(defaultValue);
String joinedDefaultValue = join(joined, separator);
if (restoreValue)
value = getPersistedString(joinedDefaultValue);
else
value = joinedDefaultValue;


setSummary(prepareSummary(Arrays.asList(unpack(value))));
setValueAndEvent(value);


/**
* Joins array of object to single string by separator
*
* Credits to kurellajunior on this post
* http://snippets.dzone.com/posts/show/91
*
* @param iterable
* any kind of iterable ex.: <code>["a", "b", "c"]</code>
* @param separator
* separetes entries ex.: <code>","</code>
* @return joined string ex.: <code>"a,b,c"</code>
*/
protected static String join(Iterable<?> iterable, String separator)
Iterator<?> oIter;
if (iterable == null




I got same error because I defined my array.xml with entries in values-large, but didn't have the file in the default values package. So I just moved array.xml into values.

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