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up vote 0 down vote favorite

I have an example about Preferences like this:

public class UserPreferences extends PreferenceActivity {
    @Override
    public void onCreate(Bundle saveInstanceState){
        super.onCreate(saveInstanceState);
        getFragmentManager().beginTransaction().replace(android.R.id.content, new MynewFracment()).commit();
    }
    public static class MynewFracment extends PreferenceFragment{
        @Override
        public void onCreate(Bundle saveInstanceState){
            super.onCreate(saveInstanceStates);
            addPreferencesFromResource(R.xml.userpreference);
        }
    }
}

But the result return is java.lang.Integer cannot be cast to java.lang.String on the line addPreferencesFromResource(R.xml.userpreferences); . I really don't know what did I do wrong here?

Update 1

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
    <CheckBoxPreference
        android:key="PREF_AUTO_UPDATE"
        android:title="Auto refresh"
        android:summary="Select to turn on automatic updateing"
        android:defaultValue="true"
        ></CheckBoxPreference>
    <ListPreference
        android:key="PREF_UPDATE_FREQ"
        android:title="Refresh frequency"
        android:summary="Frequency at which to refresh earthquake list"
        android:entries="@array/update_freq_option"
        android:entryValues="@array/update_freq_values"
        android:dialogTitle="Refresh frequency"
        android:defaultValue="60"
        ></ListPreference>
    <ListPreference
        android:key="PREF_MIN_MAG"
        android:title="Minimum magnitude"
        android:summary="Select the minimum magnitude earthquake to report"
        android:entries="@array/magnitude_options"
        android:entryValues="@array/magnitude"
        android:dialogTitle="Magnitude"
        android:defaultValue="3"
        ></ListPreference>
</PreferenceScreen>

Update 2

My R.values

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <string-array name="update_freq_option">
        <item>Every Minutes</item>
        <item>5 mins</item>
        <item>10 mins</item>
        <item>15 mins</item>
        <item>Every Hours</item>
    </string-array>

    <array name="magnitude">
        <item>3</item>
        <item>5</item>
        <item>6</item>
        <item>7</item>
        <item>8</item>
    </array>

    <string-array name="magnitude_options">
        <item>3</item>
        <item>5</item>
        <item>6</item>
        <item>7</item>
        <item>8</item>
    </string-array>

    <array name="update_freq_values">
        <item>1</item>
        <item>5</item>
        <item>10</item>
        <item>15</item>
        <item>60</item>
    </array>
</resources>

And my stacktrace

E/AndroidRuntime: FATAL EXCEPTION: main
                                                                     java.lang.RuntimeException: Unable to start activity ComponentInfo{com.begood.earthquake/com.begood.earthquake.UserPreferences}: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
                                                                         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
                                                                         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
                                                                         at android.app.ActivityThread.access$600(ActivityThread.java:130)
                                                                         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
                                                                         at android.os.Handler.dispatchMessage(Handler.java:99)
                                                                         at android.os.Looper.loop(Looper.java:137)
                                                                         at android.app.ActivityThread.main(ActivityThread.java:4745)
                                                                         at java.lang.reflect.Method.invokeNative(Native Method)
                                                                         at java.lang.reflect.Method.invoke(Method.java:511)
                                                                         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
                                                                         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
                                                                         at dalvik.system.NativeStart.main(Native Method)
                                                                      Caused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String
                                                                         at android.app.SharedPreferencesImpl.getString(SharedPreferencesImpl.java:205)
                                                                         at android.preference.Preference.getPersistedString(Preference.java:1399)
                                                                         at android.preference.ListPreference.onSetInitialValue(ListPreference.java:278)
                                                                         at android.preference.Preference.dispatchSetInitialValue(Preference.java:1315)
                                                                         at android.preference.Preference.onAttachedToHierarchy(Preference.java:1127)
                                                                         at android.preference.PreferenceGroup.addPreference(PreferenceGroup.java:156)
                                                                         at android.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:97)
                                                                         at android.preference.PreferenceGroup.addItemFromInflater(PreferenceGroup.java:38)
                                                                         at android.preference.GenericInflater.rInflate(GenericInflater.java:488)
                                                                         at android.preference.GenericInflater.inflate(GenericInflater.java:326)
                                                                         at android.preference.GenericInflater.inflate(GenericInflater.java:263)
                                                                         at android.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:269)
                                                                         at android.preference.PreferenceFragment.addPreferencesFromResource(PreferenceFragment.java:278)
                                                                         at com.begood.earthquake.UserPreferences$MynewFracment.onCreate(UserPreferences.java:20)
                                                                         at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:796)
                                                                         at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1035)
                                                                         at android.app.BackStackRecord.run(BackStackRecord.java:635)
                                                                         at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1397)
                                                                         at android.app.Activity.performStart(Activity.java:5017)
                                                                         at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2032)
                                                                         at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084) 
                                                                         at android.app.ActivityThread.access$600(ActivityThread.java:130) 
                                                                         at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195) 
                                                                         at android.os.Handler.dispatchMessage(Handler.java:99) 
                                                                         at android.os.Looper.loop(Looper.java:137) 
                                                                         at android.app.ActivityThread.main(ActivityThread.java:4745) 
                                                                         at java.lang.reflect.Method.invokeNative(Native Method) 
                                                                         at java.lang.reflect.Method.invoke(Method.java:511) 
                                                                         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 
                                                                         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
                                                                         at dalvik.system.NativeStart.main(Native Method) 
share|improve this question
    
Show your R.xml.userprefrerences. – Niels Masdorp Mar 6 at 23:21
    
Please show your resources for all the arrays you reference in the preferences XML (such as update_freq_option). – Doug Stevenson Mar 6 at 23:25
    
@NielsMasdorp Updated – Mr2uang Mar 6 at 23:38
    
@DougStevenson Updated – Mr2uang Mar 6 at 23:38
    
entryValues needs to be a string-array – njzk2 Mar 7 at 0:07
up vote 0 down vote accepted

As you can see from the stacktrace, when you call addPreferencesFromResource, the prefs are loaded, and onSetInitialValue is called to set the value of the pref to whatever was saved before, if at all.

Because it is a ListPreference, it uses getPersistedString, which tries to load a String.

This throws a ClassCastException because the pref used to be of an Integer type, and was saved as such.

You know have an existing version of your preferences on the device that is not compatible with the new version of your application.

To solve this, clear the app data, or simply uninstall it.

If you can't do that (if you have users that have the previous version of the app), you need a migration strategy, and probably to change the name of the new preference to avoid conflicts like this one.

share|improve this answer
up vote 1 down vote

Unfortunately, you have to use a string-array for the values as well, even though they are taken to be integers.

<string-array name="magnitude">
    <item>3</item>
    <item>5</item>
    <item>6</item>
    <item>7</item>
    <item>8</item>
</string-array>

<string-array name="update_freq_values">
    <item>1</item>
    <item>5</item>
    <item>10</item>
    <item>15</item>
    <item>60</item>
</string-array>
share|improve this answer
    
It still working on my early Preferences extends Activity with setContentView. – Mr2uang Mar 6 at 23:46
    
What do you mean? Is this another question? – Doug Stevenson Mar 6 at 23:47
    
Still got same error with string-array – Mr2uang Mar 6 at 23:48
    
No, I have Preferences extends Activity and UserPreferences extends PreferenceActivity in my project. The UserPreferences extends PreferenceActivity was defined in res/xml for learning . But it doesn't work. – Mr2uang Mar 6 at 23:50
    
Are you sure? I just copied your code into a test project, saw it fail, then changed to string arrays (all of them), and now it works. – Doug Stevenson Mar 6 at 23:59

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