Question

我有以下片段类：

public class Home extends Fragment {

    public static final String TAG = Home.class.getSimpleName();

    public static HomenewInstance() {
        return new Home();
    }

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

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.Homegrag, container, false);
        return v;
    }

}

当我使用它时，它是工作perferct。但是当我在这个类中添加下面的代码时，它会给我错误：

public class Home extends Fragment {
private List<RowItem> rowItems;

private static Integer[] images = { R.drawable.red, R.drawable.red,
        R.drawable.red, R.drawable.red, R.drawable.red, R.drawable.red,
        R.drawable.red, R.drawable.red };
    public static final String TAG = Home.class.getSimpleName();

    public static HomenewInstance() {
        return new Home();
    }

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

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.Homegrag, container, false);
     ListView lv = (ListView) getActivity().findViewById(R.id.myList);
    rowItems = new ArrayList<RowItem>();

    String[] titles = { "Movie1", "Movie2", "Movie3", "Movie4", "Movie5",
            "Movie6", "Movie7", "Movie8" };
    String[] descriptions = { "First Movie", "Second movie", "Third Movie",
            "Fourth Movie", "Fifth Movie", "Sixth Movie", "Seventh Movie",
            "Eighth Movie" };
    // Populate the List
    for (int i = 0; i < titles.length; i++) {
        RowItem item = new RowItem(images[i], titles[i], descriptions[i]);
        rowItems.add(item);
    }

    // Set the adapter on the ListView
    LazyAdapter adapter = new LazyAdapter(getActivity()
            .getApplicationContext(), R.layout.list_row, rowItems);
    lv.setAdapter(adapter);

    lv.setOnItemSelectedListener(new OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> arg0, View arg1,
                int arg2, long arg3) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onNothingSelected(AdapterView<?> arg0) {
            // TODO Auto-generated method stub

        }
    });
        return v;
    }

}

然后它会在lv.setAdapter(adapter);

给我错误

Logcat：

FATAL EXCEPTION: main
Process: com.paulusworld.drawernavigationtabs, PID: 11867
java.lang.NullPointerException
    at com.paulusworld.drawernavigationtabs.Rush.onCreateView(Rush.java:55)
    at android.support.v4.app.Fragment.performCreateView(Fragment.java:1500)
    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:1467)
    at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:440)
    at android.os.Handler.handleCallback(Handler.java:808)
    at android.os.Handler.dispatchMessage(Handler.java:103)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:5333)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:824)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:640)
    at dalvik.system.NativeStart.main(Native Method)

我该怎么做？我想用lazyadapter绑定列表。

Answer 1

更改此

ListView lv = (ListView) getActivity().findViewById(R.id.myList);

到

ListView lv = (ListView) v.findViewById(R.id.myList);

getActivity()表示Fragment的当前上下文，而返回的视图表示初始化View的参考。

Answer 2

尝试以下代码，如果有帮助请告诉我

  LazyAdapter adapter = new LazyAdapter(getActivity(),R.layout.list_row, rowItems);
  lv.setAdapter(adapter);

并确保lv不为空，以防万一...

并使用以下代码

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
     lv = (ListView) view.findViewById(R.id. myList);
     lv.setAdapter(adapter);
}

如何在片段类中绑定列表适配器

2 个答案: