Question

由于某种原因，在我的列表上设置适配器返回NullPointerException。我调试了应用程序，并将其缩小到以下几行：

        ArrayAdapter<AlbumModel> adapter =
                new ArrayAdapter<AlbumModel>(getActivity(), R.layout.list_item, R.id.textView,  albums);
        if (!albums.equals("")) {
            listView.setAdapter(adapter);
        }

运行调试器会显示相册（类型：列表）填充正常，并且数组适配器也会启动Object对象及其值。我已经浏览了列表，但没有看到任何空值。

enter image description here

全班都在这里：

public static class SongsFragment extends ListFragment  {
        private static final String ARG_SECTION_NUMBER = "section_number";

        public SongsFragment() {
        }

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
        }

        @Override
        public void onActivityCreated(Bundle b){
            super.onActivityCreated(b);

            ListView listView = getListView();

            List<AlbumModel> albums = null;

            try {
                XMLData parser = new XMLData();
                albums = parser.parse(getActivity().getAssets().open("data.xml"));
                Log.i("ALBUMS", albums.toString());
                ArrayAdapter<AlbumModel> adapter =
                        new ArrayAdapter<AlbumModel>(getActivity(), R.layout.list_item, R.id.textView,  albums);
                if (!albums.equals("")) {
                    listView.setAdapter(adapter);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onAttach(Activity activity) {
            super.onAttach(activity);

            ((MainActivity) activity).onSectionAttached(
                    getArguments().getInt(ARG_SECTION_NUMBER));
        }

        @Override
        public void onDetach() {
            super.onDetach();
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            // Inflate the layout for this fragment
            return inflater.inflate(R.layout.fragment_item_list, container, false);
        }

        public static SongsFragment newInstance(int sectionNumber) {
            SongsFragment fragment = new SongsFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);

            return fragment;
        }
    }

logcat：

java.lang.NullPointerException
            at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:394)
            at android.widget.ArrayAdapter.getView(ArrayAdapter.java:362)
            at android.widget.AbsListView.obtainView(AbsListView.java:2263)
            at android.widget.ListView.makeAndAddView(ListView.java:1790)
            at android.widget.ListView.fillDown(ListView.java:691)
            at android.widget.ListView.fillFromTop(ListView.java:752)
            at android.widget.ListView.layoutChildren(ListView.java:1630)
            at android.widget.AbsListView.onLayout(AbsListView.java:2091)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:690)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at com.android.internal.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:374)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.widget.FrameLayout.layoutChildren(FrameLayout.java:453)
            at android.widget.FrameLayout.onLayout(FrameLayout.java:388)
            at android.view.View.layout(View.java:14817)
            at android.view.ViewGroup.layout(ViewGroup.java:4631)
            at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:1987)
            at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1744)
            at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
            at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5670)
            at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
            at android.view.Choreographer.doCallbacks(Choreographer.java:574)
            at android.view.Choreographer.doFrame(Choreographer.java:544)
            at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)

我的代码可以在https://github.com/markbratanov/MyFitPlayer/tree/master/Player/src/main/java/com/markbratanov/myfitplayer

中完整地看到

如果已使用值初始化适配器，则不确定为什么会返回NPE。也许其中一个布局缺失，上下文不正确？整个周末我一直在这个可怕的名单上。任何帮助/意见/指导将不胜感激。

感谢。

编辑：

list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:padding="5dip" >

    <!--  ListRow Left sied Thumbnail image -->
    <LinearLayout android:id="@+id/thumbnail"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="3dip"
        android:layout_alignParentLeft="true"
        android:layout_marginRight="5dip">

        <ImageView
            android:id="@+id/list_image"
            android:layout_width="50dip"
            android:layout_height="50dip"
            android:src="@drawable/black"/>

        <TextView xmlns:android="http://schemas.android.com/apk/res/android"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:padding="10dp"
            android:textSize="16sp" />

    </LinearLayout>

使用填充的ArrayList设置列表适配器将返回NullPointerException

0 个答案: