Question

我想调用一个位于片段中的内部asynctask。我想从使用asynctask托管此片段的父片段调用asynctask。该父片段包括具有多个片段的viewpager。我知道我必须使用界面并尝试了一些东西，但它不起作用。

接口

public interface OnFragmentButtonListener {
    void onMyButtonClicked();
}

FRAGMENT

public class FragmentQueue extends SherlockFragment implements OnFragmentButtonListener
{
...
    @Override
    public void onMyButtonClicked() {
        new LoadQueueTask().execute();
    }
}

PARENT FRAGMENT

public class ParentFragment extends SherlockFragment{
...
    refresh.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            ((OnFragmentButtonListener)getActivity()).onMyButtonClicked();
        }
    });
}

错误

11-12 23:15:14.115: E/AndroidRuntime(31864): java.lang.ClassCastException: nl.name.projectname.ProjectName cannot be cast to nl.name.projectName.OnFragmentButtonListener
11-12 23:15:14.115: E/AndroidRuntime(31864):    at nl.name.projectname.fragments.ParentFragment$LoadInfoTask$1.onClick(ParentFragment.java:323)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at android.view.View.performClick(View.java:4445)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at android.view.View$PerformClick.run(View.java:18446)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at android.os.Handler.handleCallback(Handler.java:733)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at android.os.Handler.dispatchMessage(Handler.java:95)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at android.os.Looper.loop(Looper.java:136)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at android.app.ActivityThread.main(ActivityThread.java:5146)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at java.lang.reflect.Method.invokeNative(Native Method)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at java.lang.reflect.Method.invoke(Method.java:515)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:796)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:612)
11-12 23:15:14.115: E/AndroidRuntime(31864):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

看起来您正在尝试在父Activity上调用onMyButtonClicked，而不是子FragmentQueue实例。在onClick方法中，您需要获取对FragmentQueue实例的引用，然后调用onMyButtonClicked。像这样：

refresh.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        Fragment fragment = getFragmentManager().findFragmentByTag("FragmentQueue");
        if (fragment instanceof FragmentQueue) {
            ((FragmentQueue)fragment).onMyButtonClicked();
        }
    }
});

请注意，要使其正常工作，您必须将片段标记设置为＆＃34; FragmentQueue＆＃34;在构造片段时（使用XML或代码）。

从父片段调用内部asynctask

1 个答案: