Java 尝试对空对象调用虚拟方法（NullPointerException）

[类似问题的副本]

初始化

private int index=0;

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由于索引未初始化，因此它将是一个空值并导致崩溃

片段与活动不完全相同

在onViewCreated发生之前，您已经引用了一个视图movieGridView，因此它必须为“null”

看这里

除此之外，您根本不需要onCreate。savedInstanceState在onCreateView中可用

因此，删除该方法，并移动代码

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    setHasOptionsMenu(true);

    // Added this section
    if (movieDataList == null) {
        movieDataList = new ArrayList<movieData>();
    }

    if (savedInstanceState != null) {
        index = (Integer) savedInstanceState.getSerializable("POS");

        // Not sure why you had 'not empty'
        if (movieDataList.isEmpty()) {
            movieDataList.addAll(Arrays.asList((movieData[]) savedInstanceState.getSerializable("OLDMOVIEDATA"));
        }
    } // End restore instance state


    View rootView = inflater.inflate(R.layout.movie_display_fragment, container, false);

    movieGridView = (GridView) rootView.findViewById(R.id.gv_movie_display);
    movieAdapter adapter = new movieAdapter(getActivity(),movieDataList);
    movieGridView.setAdapter(adapter);
    movieGridView.setSelection(index);

    return rootView;
}

您可能希望为POS绑定.putinextra，但这是个人偏好

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当你有机会的时候，你也应该让MovieData成为一个包裹

在Java中，对于int类型，默认值为零，即0。在int值上无法获得NullPointerException非常感谢，这修复了NullPointerException！很好的解释。setSelection方法现在没有设置位置，但现在必须修复它！你有pos和index。我不知道如何处理这个问题，我现在用putint将索引保存在savebundle中，用getInt将它放到oncreateview中，然后使用smoothscrolltoposition，但它不知道该告诉您什么，但这是另一个问题。如果您有新问题，请单击按钮提问。

@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    setHasOptionsMenu(true);

    // Added this section
    if (movieDataList == null) {
        movieDataList = new ArrayList<movieData>();
    }

    if (savedInstanceState != null) {
        index = (Integer) savedInstanceState.getSerializable("POS");

        // Not sure why you had 'not empty'
        if (movieDataList.isEmpty()) {
            movieDataList.addAll(Arrays.asList((movieData[]) savedInstanceState.getSerializable("OLDMOVIEDATA"));
        }
    } // End restore instance state


    View rootView = inflater.inflate(R.layout.movie_display_fragment, container, false);

    movieGridView = (GridView) rootView.findViewById(R.id.gv_movie_display);
    movieAdapter adapter = new movieAdapter(getActivity(),movieDataList);
    movieGridView.setAdapter(adapter);
    movieGridView.setSelection(index);

    return rootView;
}