MultiSelectListPreference example
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"/>
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!
I've created MultiSelectListPreference for devices running Android in the API earlier than level 11.
- Supports ChangeListener receiving list of selected values.
- Supports automatically setting of summary.
- Examples attached.
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 = "\u0001\u0007\u001D\u0007\u0001";
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 || entryValues == null
|| entries.length != entryValues.length) {
throw new IllegalStateException(
"MultiSelectListPreference requires an entries array and an entryValues "
+ "array which are both the same length");
}
restoreCheckedEntries();
OnMultiChoiceClickListener listener = new DialogInterface.OnMultiChoiceClickListener() {
public void onClick(DialogInterface dialog, int which, boolean val) {
entryChecked[which] = val;
}
};
builder.setMultiChoiceItems(entries, entryChecked, listener);
}
private CharSequence[] unpack(CharSequence val) {
if (val == null || "".equals(val)) {
return new CharSequence[0];
} else {
return ((String) val).split(separator);
}
}
/**
* 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 || (!(oIter = iterable.iterator()).hasNext()))
return "";
StringBuilder oBuilder = new StringBuilder(String.valueOf(oIter.next()));
while (oIter.hasNext())
oBuilder.append(separator).append(oIter.next());
return oBuilder.toString();
}
}
You can do it on runtime just setting values/entries like this
findPreference<MultiSelectListPreference>(getString(R.string.preference_key_some_apps))?.apply {
val entryDisplay =
listOf("Facebook Messenger", "Whatsapp", "Telegram", "SMS").toTypedArray()
val entryValuesApps = listOf(
Constants.FACEBOOK_MESSENGER_PACKAGE_NAME,
Constants.WHATSAPP_PACKAGE_NAME,
Constants.TELEGRAM_PACKAGE_NAME,
Constants.SMS_MESSENGER_PACKAGE_NAME_HOLDER
).toTypedArray()
entries = entryDisplay
this.entryValues = entryValuesApps
}