Android ClassCastException列表无法强制转换为android.app.Fragment

时间：2014-08-06 04:01:14

标签： android exception android-fragments casting

我在这里看到了这个问题，但没有解决我的问题。我的片段扩展了一个名为CommonListFragment的类，它扩展了Fragment类。我托管片段的Activity扩展了一个名为CommonActivity的类，它扩展了FragmentActivity类。一切似乎都没问题，为什么会出现以下错误？

  

Android ClassCastException列表无法转换为android.app.Fragment

正如您可以看到的那样，Android正在尝试将我的List类转换为android.app.Fragment，而它应该真正转换为android.support.v4.app.Fragment。 My List类最终扩展了Fragment类（android.support.v4.app.Fragment）。我的最小和目标SDK也是Android 2.2。所以，如果我尝试导入'android.app.Fragment'，则会出现编译错误。那么我如何强制Android将我的List识别为android.support.v4.app.Fragment？

CommonActivity.java： 

public class CommonActivity extends FragmentActivity {
    ...
}

ListsContainer.java： 

public class ListsContainer extends CommonActivity implements OnListChangedListener {

    private int m_orientation ;
    private static int EXTRA_LARGE = 4;

    @Override
    public void onCreate(Bundle savedInstanceState) {
    m_ctx = this;
    setContentView(R.layout.lists_container);
    ...

CommonListFragment： 

 public class CommonListFragment extends Fragment implements  IOnEditTextClickedListener,
                                                                 IOnItemCheckedListener,
                                                                 IOnDismissDialog,
                                                                 ISettings,
                                                                 OnClickListener
{
        public void onItemChecked(int pos,boolean checked,String sGroup,String sList){

        }
        ...
}

lists_container.xml： 

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="horizontal" >

    <fragment
        android:id="@+id/listsFragment"
        android:layout_width="0dp"
        android:layout_weight="1"
        android:layout_height="match_parent"
        class="com.onesix.myApp.Lists" ></fragment>
    <fragment
        android:id="@+id/listFragment"
        android:layout_width="0dp"
        android:layout_weight="2"
        android:layout_height="match_parent"
        class="com.onesix.myApp.List" >
        <!-- Preview: layout=@layout/details -->
    </fragment>

</LinearLayout>

logcat的 

08-06 00:15:44.228: W/ServerManagedPolicy(7472): Licence retry count (GR) missing, grace period disabled
08-06 00:17:35.207: W/dalvikvm(7472): threadid=1: thread exiting with uncaught exception (group=0x41814970)
08-06 00:17:35.287: E/AndroidRuntime(7472): FATAL EXCEPTION: main
08-06 00:17:35.287: E/AndroidRuntime(7472): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.onesix.myApp/com.onesix.myApp.ListsContainer}: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2517)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2574)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.ActivityThread.access$600(ActivityThread.java:162)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1413)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.os.Looper.loop(Looper.java:158)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.ActivityThread.main(ActivityThread.java:5789)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at java.lang.reflect.Method.invokeNative(Native Method)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at java.lang.reflect.Method.invoke(Method.java:525)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:843)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at dalvik.system.NativeStart.main(Native Method)
08-06 00:17:35.287: E/AndroidRuntime(7472): Caused by: android.view.InflateException: Binary XML file line #7: Error inflating class fragment
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.view.LayoutInflater.inflate(LayoutInflater.java:353)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:339)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.Activity.setContentView(Activity.java:1944)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at com.onesix.myApp.ListsContainer.onCreate(ListsContainer.java:18)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.Activity.performCreate(Activity.java:5195)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1111)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2473)
08-06 00:17:35.287: E/AndroidRuntime(7472):     ... 11 more
08-06 00:17:35.287: E/AndroidRuntime(7472): Caused by: java.lang.ClassCastException: com.onesix.myApp.Lists cannot be cast to android.app.Fragment
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.Fragment.instantiate(Fragment.java:617)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.Fragment.instantiate(Fragment.java:592)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.app.Activity.onCreateView(Activity.java:4800)
08-06 00:17:35.287: E/AndroidRuntime(7472):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:689)

List.java： 

public class List extends CommonListFragment implements IOnDismissYesNoListener
{

    @Override
    public View  onCreateView(LayoutInflater inflater, ViewGroup container,Bundle  savedInstanceState) 
    {
        //setContentView(R.layout.list);
        View view = inflater.inflate(R.layout.list,container, false);
        //super.onCreate(savedInstanceState);

        return view;
    }

    ...
}

最新的LOGCAT 

08-06 01:05:00.736: E/AndroidRuntime(15588): Caused by: java.lang.ClassCastException: com.onesix.myApp.Lists cannot be cast to android.app.Fragment
08-06 01:05:00.736: E/AndroidRuntime(15588):    at android.app.Fragment.instantiate(Fragment.java:617)
08-06 01:05:00.736: E/AndroidRuntime(15588):    at android.app.Fragment.instantiate(Fragment.java:592)
08-06 01:05:00.736: E/AndroidRuntime(15588):    at android.app.Activity.onCreateView(Activity.java:4800)
08-06 01:05:00.736: E/AndroidRuntime(15588):    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:689)

有人有什么想法吗？我已经在SO上检查了关于这个主题的每个问题......

1 个答案:

答案 0 :(得分：0)

<强>问题： 

class="com.onesix.myApp.List"

在您的班级List中，您正在导入支持库的片段而不是默认的Android片段，因为您使用的是FragmentActivity，这意味着您必须使用非支持库中的片段

确保所有片段类特别在List class导入此内容：

import android.app.Fragment;

编辑：

 <fragment
    android:id="@+id/listFragment"
    android:layout_width="0dp"
    android:layout_weight="2"
    android:layout_height="match_parent"
    android:name="com.onesix.myApp.List" >
    <!-- Preview: layout=@layout/details -->
</fragment>
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