Android - 首選項 - ClassCastException

我測試了一個標準的偏好教程，沒有任何問題..但在本教程中（在所有類似的例子中），首選項活動的目的是從主要活動內部開始的...Android - 首選項 - ClassCastException

我試圖複製我的應用程序裏面的簡單的測試代碼，但首活動的意圖是從列表活動中開始......（從菜單欄）

public class TrainingListActivity extends FragmentActivity implements 
     TrainingListFragment.Callbacks { 

    // ..... 
    public void settingsActivity() { 
     Intent settingsActivity = new Intent(this, Preferences.class); 
     startActivity(settingsActivity); 
    } 
}

，所以我說這在manifest.xml指示TrainingListActivity作爲父活動

<activity 
    android:name="com.swimtechtest.swimmer.TrainingListActivity" 
    android:label="@string/app_name" > 
    android:theme="@android:style/Theme.Black.NoTitleBar" > 
    <intent-filter> 
     <action android:name="android.intent.action.MAIN" /> 
     <category android:name="android.intent.category.LAUNCHER" /> 
    </intent-filter> 
</activity> 
<activity 
    android:name="com.swimtechtest.swimmer.Preferences" 
    android:label="@string/title_preferences" 
    android:parentActivityName=".Preferences" > 
    <meta-data 
     android:name="android.support.PARENT_ACTIVITY" 
     android:value=".TrainingListActivity" /> 
</activity>

，但在運行它時，我得到一個運行時錯誤：

android.preference.Preference不能轉換到android.preference.GenericInflater $父

這似乎在提高首選項onCreate()方法的結束，setDefaultValues ...任何線索？

@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    getFragmentManager().beginTransaction() 
     .replace(android.R.id.content, new PrefsFragment()).commit(); 
    PreferenceManager.setDefaultValues(Preferences.this, R.xml.preferences, 
     false); 
}

的preferences.xml

<?xml version="1.0" encoding="utf-8"?> 
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" > 
<PreferenceCategory android:title="My list of Preferences" > 
    <CheckBoxPreference 
     android:defaultValue="false" 
     android:key="checkboxPref" 
     android:summary="This preference can be true or false" 
     android:title="Checkbox Preference" /> 
    <ListPreference 
     android:defaultValue="digiGreen" 
     android:entries="@array/listArray" 
     android:entryValues="@array/listValues" 
     android:key="listPref" 
     android:summary="This preference allows to select an item in a array" 
     android:title="Your favorite Pet" /> 
    <EditTextPreference 
     android:name="EditText Preference" 
     android:defaultValue="Nothing" 
     android:key="editTextPref" 
     android:summary="This allows you to enter a string" 
     android:title="Edit This Text" /> 
    <RingtonePreference 
     android:name="Ringtone Preference" 
     android:key="ringtonePref" 
     android:summary="Select a ringtone" 
     android:title="Ringtones" /> 
    <PreferenceScreen 
     android:key="SecondPrefScreen" 
     android:summary="This is a sub PreferenceScreen" 
     android:title="Secondary Level" > 
     <intent 
      android:action="android.intent.action.VIEW" 
      android:targetClass="com.example.preferencesexample.Preferences2" 
      android:targetPackage="com.example.preferencesexample" /> 
    </PreferenceScreen> 
    <Preference 
     android:key="customPref" 
     android:summary="This works almost like a button" 
     android:title="Custom Preference" /> 
</PreferenceCategory> 
</PreferenceScreen>

consolelog

FATAL EXCEPTION: main 
Process: com.swimtechtest.swimmer, PID: 9690 
java.lang.RuntimeException: Unable to start activity  
    ComponentInfo{com.swimtechtest.swimmer/com.swimtechtest.swimmer.Preferences}: 
    java.lang.ClassCastException: android.preference.Preference cannot be cast to 
    android.preference.GenericInflater$Parent 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195) 
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245) 
at android.app.ActivityThread.access$800(ActivityThread.java:135) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:136) 
    .... 
    Caused by: java.lang.ClassCastException: android.preference.Preference cannot be cast to android.preference.GenericInflater$Parent 
at android.preference.GenericInflater.inflate(GenericInflater.java:320) 
at android.preference.GenericInflater.inflate(GenericInflater.java:263) 
at android.preference.PreferenceManager.inflateFromResource(PreferenceManager.java:272) 
at android.preference.PreferenceManager.setDefaultValues(PreferenceManager.java:485) 
at android.preference.PreferenceManager.setDefaultValues(PreferenceManager.java:444) 
at com.swimtechtest.swimmer.Preferences.onCreate(Preferences.java:19) 
at android.app.Activity.performCreate(Activity.java:5231) 
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)

來源

2014-01-19 erwin

R.xml.preferences裏面是什麼？ –

感謝您指出它...我添加了在崩潰前使用的preferences.xml ...再次測試它沒有PreferenceScreen（第二預製屏幕）它運行良好！所以我需要進入它..但總體首選項活動在我的projet內運行良好... – erwin

你的意思是：

<activity 
    android:name="com.swimtechtest.swimmer.Preferences" 
    android:label="@string/title_preferences" 
    android:parentActivityName="com.swimtechtest.swimmer.TrainingListActivity" > 
    <meta-data 
     android:name="android.support.PARENT_ACTIVITY" 
     android:value=".TrainingListActivity" /> 
</activity>

？

來源

2014-01-19 15:31:28

是的，這是正確的.... – erwin

Android - 首選項 - ClassCastException

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