Question

当我点击ListFragment中的任何元素时，我试图在MyCustomView中接收一个CallBack，它是一个表示Fragment的类（或者我们可以说，它是Fragment的视图）。日志附在下面：

04-12 11:56:04.321: D/FirstFragment(762): setting ui listener callback
04-12 11:56:04.321: D/AndroidRuntime(762): Shutting down VM
04-12 11:56:04.321: W/dalvikvm(762): threadid=1: thread exiting with uncaught exception (group=0x40015560)
04-12 11:56:04.331: E/AndroidRuntime(762): FATAL EXCEPTION: main
04-12 11:56:04.331: E/AndroidRuntime(762): java.lang.ClassCastException: com.gaurav.listing.ListFragmentActivity
04-12 11:56:04.331: E/AndroidRuntime(762): at com.gaurav.listing.FirstFragment.onListItemClick(FirstFragment.java:66)
04-12 11:56:04.331: E/AndroidRuntime(762): at android.support.v4.app.ListFragment$2.onItemClick(ListFragment.java:58)
04-12 11:56:04.331: E/AndroidRuntime(762): at android.widget.AdapterView.performItemClick(AdapterView.java:284)
04-12 11:56:04.331: E/AndroidRuntime(762): at android.widget.ListView.performItemClick(ListView.java:3513)
04-12 11:56:04.331: E/AndroidRuntime(762): at 

android.widget.AbsListView$PerformClick.run(AbsListView.java:1812)
    04-12 11:56:04.331: E/AndroidRuntime(762): at android.os.Handler.handleCallback(Handler.java:587)
    04-12 11:56:04.331: E/AndroidRuntime(762): at android.os.Handler.dispatchMessage(Handler.java:92)
    04-12 11:56:04.331: E/AndroidRuntime(762): at android.os.Looper.loop(Looper.java:123)
    04-12 11:56:04.331: E/AndroidRuntime(762): at android.app.ActivityThread.main(ActivityThread.java:3683)
    04-12 11:56:04.331: E/AndroidRuntime(762): at java.lang.reflect.Method.invokeNative(Native Method)
    04-12 11:56:04.331: E/AndroidRuntime(762): at java.lang.reflect.Method.invoke(Method.java:507)
    04-12 11:56:04.331: E/AndroidRuntime(762): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
    04-12 11:56:04.331: E/AndroidRuntime(762): at 

04-12 11:56:04.331: E/AndroidRuntime(762): at dalvik.system.NativeStart.main(Native Method)com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)

然后我附上Fragment的代码片段，我试图设置这个回叫。

package com.gaurav.listing;

import android.app.Activity;
public class FirstFragment extends ListFragment {
private static final String TAG = "FirstFragment";
public UIListener uiCallback;
ArrayAdapter adapter;
ListView list;
View view;
String[] values;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// some code here...
}
@Override
public void onResume() {
// some code here...
}
Activity activity = null;
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
this.activity = activity;
uiCallback = (UIListener) activity;
} catch (ClassCastException e) {
}
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
Log.d("FirstFragment", "onListItemClick");
String shape = l.getItemAtPosition(position).toString();
Log.d(TAG, shape);
if (null == uiCallback) {
Log.d("FirstFragment", "setting ui listener callback");
// problem occur here
uiCallback = (UIListener) activity;

}
uiCallback.onButtonClicked(l, v, position, id, shape);
}
}

请告诉我如何解决此问题。关于我希望收到回调的目标的更多细节：片段的id：second_fragment 视图类的片段：SecondFragment.java

Answer 1

因为您要调用实现UIListener接口的类。我假设你的SecondFragment类实现了UIListener接口。

然后你应该尝试像

这样的东西

    uiCallback = (SecondFragment) getActivity().getSupportFragmentManager().findFragmentById(R.id.second_fragment);

这将是五个视图片段视图和类型转换我猜不会有任何问题。

从Fragment设置customView的回调时出现ClassCastException

1 个答案: