我很难找到Android API中提供的MultiSelectListPreference的好例子。我见过许多对this blog的引用，这是我想要的最终结果，我不想为我想要实现的每个多选择首选项创建一个类。
最后，我希望看到一个简单的多选对话框的首选项xml（我将动态填充这些值），以及调用addPreferencesFromResource(R.xml.preferences);
目前，我有：
<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" />
当我尝试在我的Activities onCreate调用中调用addPreferencesFromResource时，我收到以下错误：
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 ComponentInfo{com.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
我期待你的回复！
答案 0 :(得分：44)
您需要指定defaultValues属性
<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"
/>
如果您不想要默认值，请在strings.xml中创建一个空数组
<string-array name="empty_array"/>
答案 1 :(得分：12)
Sigrist是正确的，以解决您所看到的初始错误。它需要提供的默认值，即使它是空的。这对我有帮助，因为我想在 RUNTIME 中提供值，但不要完全实现。
请参阅此代码，了解我如何在运行时提供值，而不必处理完整的实现。
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[]{}));
}
}
在我的strings.xml中
<string-array name="pref_calendar_list_default">
</string-array>
在我的preferences.xml
中<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"/>
我知道这是一个古老的问题，但它帮助了我，所以这是我的答案！
答案 2 :(得分：3)
我为早于11级的API中运行Android的设备创建了MultiSelectListPreference。
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();
}
}
答案 3 :(得分：1)
您可以在运行时只需设置这样的值/条目即可
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
}
答案 4 :(得分：0)
我遇到了同样的错误，因为我用 values-large 中的条目定义了 array.xml ，但没有默认 values < / strong>软件包。所以我只是将 array.xml 移到了值。