java - 在 Fragment 中创建 View 时出错

Question

我创建了一个具有 3 个 fragment 布局的 Activity，用户将在其中滑动屏幕以显示另一个 fragment 。

在我的第一个 fragment 中，我计划使用一个 ListView 来显示用户的信息。但是，我通常用于扩展 Activity 的代码不适用于扩展 fragment 。我进行了一些研究，最终摆脱了红线，但是当我显示该 fragment 时我的应用程序崩溃了。

这是我的代码:

public class LayoutOne extends ListFragment {
ListView myInfoList;
String[] items = {"Item 1", "Item 2"};
ArrayAdapter<CharSequence> adapter;

public static Fragment newInstance(Context context) {
    LayoutOne f = new LayoutOne();  

    return f;
}

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

    return view;
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onActivityCreated(savedInstanceState);
    myInfoList = getListView();
    adapter = new ArrayAdapter<CharSequence>(getActivity().getApplicationContext(), android.R.layout.simple_list_item_1, items);
    myInfoList.setAdapter(adapter);
}


}

这是我的日志猫:

06-16 17:57:16.150: D/AndroidRuntime(20378): Shutting down VM 06-16 17:57:16.150: W/dalvikvm(20378): threadid=1: thread exiting with uncaught exception (group=0x40ff9930) 06-16 17:57:16.158: E/AndroidRuntime(20378): FATAL EXCEPTION: main 06-16 17:57:16.158: E/AndroidRuntime(20378): java.lang.RuntimeException: Your content must have a ListView whose id attribute is 'android.R.id.list' 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.app.ListFragment.ensureList(ListFragment.java:344) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.app.ListFragment.onViewCreated(ListFragment.java:145) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:884) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1080) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:622) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1416) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:431) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:139) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.view.ViewPager.populate(ViewPager.java:804) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1016) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.View.measure(View.java:15523) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.widget.LinearLayout.measureVertical(LinearLayout.java:695) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.View.measure(View.java:15523) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.View.measure(View.java:15523) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.widget.LinearLayout.measureVertical(LinearLayout.java:847) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.widget.LinearLayout.onMeasure(LinearLayout.java:588) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.View.measure(View.java:15523) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.widget.FrameLayout.onMeasure(FrameLayout.java:310) 06-16 17:57:16.158: E/AndroidRuntime(20378): at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2434) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.View.measure(View.java:15523) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.Choreographer.doCallbacks(Choreographer.java:562) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.Choreographer.doFrame(Choreographer.java:532) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.os.Handler.handleCallback(Handler.java:725) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.os.Handler.dispatchMessage(Handler.java:92) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.os.Looper.loop(Looper.java:137) 06-16 17:57:16.158: E/AndroidRuntime(20378): at android.app.ActivityThread.main(ActivityThread.java:5233) 06-16 17:57:16.158: E/AndroidRuntime(20378): at java.lang.reflect.Method.invokeNative(Native Method) 06-16 17:57:16.158: E/AndroidRuntime(20378): at java.lang.reflect.Method.invoke(Method.java:511) 06-16 17:57:16.158: E/AndroidRuntime(20378): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:799) 06-16 17:57:16.158: E/AndroidRuntime(20378): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:566) 06-16 17:57:16.158: E/AndroidRuntime(20378): at dalvik.system.NativeStart.main(Native Method)

Answer 1

您永远不会初始化 myInfoList。据我所知，您的类(class)应该扩展 ListFragment 而不是 Fragment。

您的 onCreateView 应该膨胀包含 ListView 的布局，您应该移动

adapter = new ArrayAdapter<CharSequence>(getActivity().getApplicationContext(), android.R.layout.simple_list_item_1, items);
myInfoList.setAdapter(adapter); 

在 onActivityCreate 中:

public void onActivityCreated(Bundle savedInstanceState) {
    myInfoList = getListView();
    adapter = new ArrayAdapter<CharSequence>(getActivity().getApplicationContext(), android.R.layout.simple_list_item_1, items);
    myInfoList.setAdapter(adapter); 
}

你的 ListView 的 id 必须是

android:id="@id/android:list"