Question

以下代码会导致应用程序在启动时崩溃：

 public class ListFragment extends Fragment {

    ListView list;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        ListView view = (ListView) inflater.inflate(R.layout.list_layout, container, false);
        view.setAdapter(new MyAdapter(getActivity()));
        return view;
    }
}

但是，这段代码：

    public class ListFragment extends Fragment {

    ListView list;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.list_layout, container, false);
        return view;
    }
}

运行良好，但没有做我想要的，因为它没有显示ListView。有人能看出为什么会发生这种情况的原因吗？

这是我运行第一个代码时的日志：

11-19 12:28:58.453    3244-3244/com.example.dan.myapplication E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.ClassCastException: android.widget.LinearLayout cannot be cast to android.widget.ListView
        at com.example.dan.myapplication.ListFragment.onCreateView(ListFragment.java:31)
        at android.support.v4.app.Fragment.performCreateView(Fragment.java:1478)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:927)
        at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1104)
        at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:682)
        at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1460)
        at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:472)
        at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:1068)
        at android.support.v4.view.ViewPager.populate(ViewPager.java:914)
        at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1436)
        at android.view.View.measure(View.java:15518)
        at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:681)
        at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461)
        at android.view.View.measure(View.java:15518)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at android.view.View.measure(View.java:15518)
        at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
        at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
        at android.view.View.measure(View.java:15518)
        at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4825)
        at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
        at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176)
        at android.view.View.measure(View.java:15518)
        at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874)
        at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
        at android.view.Choreographer.doCallbacks(Choreographer.java:562)
        at android.view.Choreographer.doFrame(Choreographer.java:532)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
        at android.os.Handler.handleCallback(Handler.java:725)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:5041)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
        at dalvik.system.NativeStart.main(Native Method)

List Fragment的XML：

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

    <ListView
        android:id="@+id/list"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </ListView>

</LinearLayout>

我在列表中还有一行XML，其中包含两个TextView和一个ImageView，ListAdapter在getView（）中膨胀。

Answer 1

使用view findViewById ListView：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.list_layout, container, false);
    list = (ListView) view.findViewById(R.id.list);
    //set the adapter, etc
    return view;
}

Answer 2

问题是，您将片段视图转换为列表视图。尝试首先投射到视图，然后找到带有视图的ListView。

从片段中的OnCreateView返回ListView

2 个答案: