java - android clear in costom arrayadapter java.lang.UnsupportedOperationException

Question

我想在我的 CostomArrayAdapter 中使用 clear()，但我总是得到这个错误:

09-08 18:15:01.960: E/AndroidRuntime(27192): FATAL EXCEPTION: main
09-08 18:15:01.960: E/AndroidRuntime(27192): java.lang.UnsupportedOperationException
09-08 18:15:01.960: E/AndroidRuntime(27192):    at java.util.AbstractList.remove(AbstractList.java:638)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at java.util.AbstractList$SimpleListIterator.remove(AbstractList.java:75)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at java.util.AbstractList.removeRange(AbstractList.java:658)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at java.util.AbstractList.clear(AbstractList.java:466)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.ArrayAdapter.clear(ArrayAdapter.java:258)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at de.fterhorst.pictoriusvertretungsplan.SimpleArrayadapterDay.dayempty(SimpleArrayadapterDay.java:235)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at de.fterhorst.pictoriusvertretungsplan.SimpleArrayadapterDay.getView(SimpleArrayadapterDay.java:177)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.AbsListView.obtainView(AbsListView.java:2177)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.ListView.makeAndAddView(ListView.java:1840)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.ListView.fillDown(ListView.java:675)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.ListView.fillFromTop(ListView.java:736)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.ListView.layoutChildren(ListView.java:1655)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.AbsListView.onLayout(AbsListView.java:2012)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.View.layout(View.java:14289)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.ViewGroup.layout(ViewGroup.java:4559)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1671)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1525)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.LinearLayout.onLayout(LinearLayout.java:1434)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.View.layout(View.java:14289)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.ViewGroup.layout(ViewGroup.java:4559)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.View.layout(View.java:14289)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.ViewGroup.layout(ViewGroup.java:4559)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at com.android.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:349)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.View.layout(View.java:14289)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.ViewGroup.layout(ViewGroup.java:4559)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.widget.FrameLayout.onLayout(FrameLayout.java:448)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.View.layout(View.java:14289)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.ViewGroup.layout(ViewGroup.java:4559)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1976)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1730)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5481)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.Choreographer.doCallbacks(Choreographer.java:562)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.Choreographer.doFrame(Choreographer.java:532)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.os.Handler.handleCallback(Handler.java:730)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.os.Handler.dispatchMessage(Handler.java:92)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.os.Looper.loop(Looper.java:137)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at android.app.ActivityThread.main(ActivityThread.java:5103)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at java.lang.reflect.Method.invokeNative(Native Method)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at java.lang.reflect.Method.invoke(Method.java:525)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
09-08 18:15:01.960: E/AndroidRuntime(27192):    at dalvik.system.NativeStart.main(Native Method)

当我这样做的时候:

这个.clear();this.notifyDataSetChanged();

在我的 ArrayAdapter 上:

public class CostomArrayAdapter extends ArrayAdapter<String>

我可以在数组适配器上使用 clear() 吗？我希望有人能帮助我。

Answer 1

您遇到的错误不是由于在 ArrayAdapter 上调用 clear()。您正在使用 List 实现(可能是默认的)，它没有实现 clear() 方法，因此也没有实现父类，即。使用了 AbstractList 实现，它抛出 UnsupportedOperationException。

如果你传递一个数组给构造函数

public ArrayAdapter(Context context, int resource, T[] objects) {
    init(context, resource, 0, Arrays.asList(objects));
}

它调用 Arrays.asList() 返回一个 List，你不能 add() remove() 来自或 clear()。

使用这个构造函数

public ArrayAdapter(Context context, int resource, List<T> objects) {
    init(context, resource, 0, objects);
}

通过传递包含您的对象的 LinkedList 或 ArrayList。