java - 有趣的类CastException

Question

我有这门课:

public class RiddlesHolder extends Application {

    String[] funnyRiddles = { "1",
            "1",
            "1",
            "1", };

    String[] funnyRiddlesAnswers = { "1", "1", "1", "1",
            "1", };

    String[] animalRiddlesList = {
            "2",
            "2",
            "2" };

    String[] animalRiddlesAnswersList = { "2", "2", "2" };

    public String[] getFunnyRiddles() {
        return funnyRiddles;
    }

    public String getFunnyRiddlesByPos(int position) {
        return funnyRiddles[position];
    }

    public String[] getFunnyRiddlesAnswers() {
        return funnyRiddlesAnswers;
    }

    public String[] getAnimalRiddlesList() {
        return animalRiddlesList;
    }

    public String[] getAnimalRiddlesAnswersList() {
        return animalRiddlesAnswersList;
    }

}

现在我正尝试在一个 Activity 中调用它，下面是方法(我正在使用一个 fragment ):

public static class PlaceholderFragment extends Fragment {

    public PlaceholderFragment() {
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_funny_riddles,
                container, false);

        final RiddlesHolder riddles = (RiddlesHolder)getActivity().getApplication();

        Random rnd = new Random();

        int randomRiddle = rnd.nextInt(riddles.getFunnyRiddles().length);

        TextView text = (TextView) rootView.findViewById(R.id.txtAnimalRiddle);
        text.setText(riddles.getFunnyRiddlesByPos(randomRiddle));

        return rootView;
    }
}

但是它抛出这个异常:

05-03 04:55:21.367: E/AndroidRuntime(1645): FATAL EXCEPTION: main
05-03 04:55:21.367: E/AndroidRuntime(1645): Process: com.gelasoft.gatanki, PID: 1645
05-03 04:55:21.367: E/AndroidRuntime(1645): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.gelasoft.gatanki/com.gelasoft.gatanki.FunnyRiddles}: java.lang.ClassCastException: android.app.Application cannot be cast to com.gelasoft.tools.RiddlesHolder
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.os.Handler.dispatchMessage(Handler.java:102)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.os.Looper.loop(Looper.java:136)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.app.ActivityThread.main(ActivityThread.java:5017)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at java.lang.reflect.Method.invokeNative(Native Method)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at java.lang.reflect.Method.invoke(Method.java:515)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at dalvik.system.NativeStart.main(Native Method)
05-03 04:55:21.367: E/AndroidRuntime(1645): Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to com.gelasoft.tools.RiddlesHolder
05-03 04:55:21.367: E/AndroidRuntime(1645):     at com.gelasoft.gatanki.FunnyRiddles$PlaceholderFragment.onCreateView(FunnyRiddles.java:66)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:938)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1115)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1478)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:570)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1171)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.app.Activity.performStart(Activity.java:5241)
05-03 04:55:21.367: E/AndroidRuntime(1645):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2168)
05-03 04:55:21.367: E/AndroidRuntime(1645):     ... 11 more

我在这里错过了什么？我知道它真的很小，但我想不通，因为我对 android 不是很熟悉。

Answer 1

您需要编辑 <application.../>在你的 AndroidManifest 中标记指向您的自定义 Application .例如:

<application
    android:name="your.path.to.RiddlesHolder"
    ... >        
</application>