我对 Android Studio 中的 PreferenceScreen 有疑问。我使用 MultiSelectListPreference 并没有收到错误，但是当我使用 ListPreference 时，我收到错误并且没有打开设置活动。
<PreferenceCategory
android:title="Time Table Setting">
<ListPreference
android:key="Header_List"
android:entries="@array/setting_header_list"
android:entryValues="@array/setting_header_values"
android:title="Display Dates"
android:summary="Monday to Friday, Saturday or Sunday"/>
</PreferenceCategory>
<Preference
android:key="Restart"
android:title="Save"/>
如果您有任何建议，请帮助我。谢谢
这是我收到的错误消息
2020-03-21 22:06:26.212 14206-14206/com.pythontaro.personaltimetable E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.name, PID: 14206
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.name.appname/com.name.appname.setting.SettingsActivity}: java.lang.ClassCastException: java.util.HashSet cannot be cast to java.lang.String
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
Caused by: java.lang.ClassCastException: java.util.HashSet cannot be cast to java.lang.String
at android.app.SharedPreferencesImpl.getString(SharedPreferencesImpl.java:225)
at androidx.preference.Preference.getPersistedString(Preference.java:1686)
at androidx.preference.ListPreference.onSetInitialValue(ListPreference.java:255)
at androidx.preference.Preference.onSetInitialValue(Preference.java:1614)
at androidx.preference.Preference.dispatchSetInitialValue(Preference.java:1587)
at androidx.preference.Preference.onAttachedToHierarchy(Preference.java:1311)
at androidx.preference.Preference.onAttachedToHierarchy(Preference.java:1326)
at androidx.preference.PreferenceGroup.addPreference(PreferenceGroup.java:249)
at androidx.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:170)
at androidx.preference.PreferenceInflater.rInflate(PreferenceInflater.java:345)
at androidx.preference.PreferenceInflater.rInflate(PreferenceInflater.java:346)
at androidx.preference.PreferenceInflater.inflate(PreferenceInflater.java:157)
at androidx.preference.PreferenceInflater.inflate(PreferenceInflater.java:109)
at androidx.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:216)
at androidx.preference.PreferenceFragmentCompat.addPreferencesFromResource(PreferenceFragmentCompat.java:361)
at com.name.appname.setting.SettingsActivity$SettingsFragment.onCreatePreferences(SettingsActivity.java:28)
at androidx.preference.PreferenceFragmentCompat.onCreate(PreferenceFragmentCompat.java:160)
at androidx.fragment.app.Fragment.performCreate(Fragment.java:2684)
at androidx.fragment.app.FragmentStateManager.create(FragmentStateManager.java:280)
at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1175)
at androidx.fragment.app.FragmentTransition.addToFirstInLastOut(FragmentTransition.java:1255)
at androidx.fragment.app.FragmentTransition.calculateFragments(FragmentTransition.java:1138)
at androidx.fragment.app.FragmentTransition.startTransitions(FragmentTransition.java:136)
at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1989)
at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1947)
at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1849)
at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:2629)
at androidx.fragment.app.FragmentManager.dispatchActivityCreated(FragmentManager.java:2577)
at androidx.fragment.app.FragmentController.dispatchActivityCreated(FragmentController.java:247)
at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:541)
at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1248)
at android.app.Activity.performStart(Activity.java:6679)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2609)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
这是设置活动类中的代码
public class SettingsActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.settings_activity);
getSupportFragmentManager()
.beginTransaction()
.replace(R.id.settings, new SettingsFragment())
.commit();
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
actionBar.setDisplayHomeAsUpEnabled(true);
}
}
public static class SettingsFragment extends PreferenceFragmentCompat {
@Override
public void onCreatePreferences(Bundle savedInstanceState, String rootKey) {
addPreferencesFromResource(R.xml.settings);
}
}}
这是字符串值的代码
<!--Setting-->
<string-array name="setting_header_list">
<item>"Friday(default)"</item>
<item>"Saturday"</item>
<item>"Sunday"</item>
</string-array>
<string-array name="setting_header_values">
<item>0</item>
<item>1</item>
<item>2</item>
</string-array>
这是 SharedPreferencesImpl.java 中第 225 行的代码
final StructStat stat;
try {
/*
* Metadata operations don't usually count as a block guard
* violation, but we explicitly want this one.
*/
BlockGuard.getThreadPolicy().onReadFromDisk();
stat = Os.stat(mFile.getPath());
} catch (ErrnoException e) {
return true;
}