让一个表里面的片段，错误是在一个空对象引用

Question

这是代码：

public class Persion1_fragment extends Fragment{
    Context mContext;
    @Override
    public void onAttach(Activity activity){
        super.onAttach(activity);
        this.mContext = activity;
    }
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

        TableFixHeaders tableFixHeaders = (TableFixHeaders)getActivity().findViewById(R.id.table);
        String [][] str=new String[][] {
                {
                        "Header 1",
                        "Header 2",
                        "Header 3",
                        "Header 4",
                        "Header 5",
                        "Header 6" },
        };

        MatrixTableAdapter<String> matrixTableAdapter = new MatrixTableAdapter<String>(this.mContext,str);
        tableFixHeaders.setAdapter(matrixTableAdapter);
        return inflater.inflate(R.layout.persion3, container, false);
    }
}

这是错误：

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.inqbarna.tablefixheaders.TableFixHeaders.setAdapter(com.inqbarna.tablefixheaders.adapters.TableAdapter)' on a null object reference

我正在使用TableFixHeaders的开源版本。 我非常期待帮助。

Answer 1

TableFixHeaders tableFixHeaders = (TableFixHeaders)getActivity().findViewById(R.id.table);

这一行存在一些问题，因此tableFixHeaders实际上是null。
您应首先使视图膨胀，然后从膨胀的视图中查找子视图。

在onCreateView（）中尝试此代码。

View view = inflater.inflate(R.layout.persion3, container, false);
TableFixHeaders tableFixHeaders = (TableFixHeaders)view.findViewById(R.id.table);
String [][] str=new String[][] {
        {
                "Header 1",
                "Header 2",
                "Header 3",
                "Header 4",
                "Header 5",
                "Header 6" },
};

MatrixTableAdapter<String> matrixTableAdapter = new MatrixTableAdapter<String>(this.mContext,str);
tableFixHeaders.setAdapter(matrixTableAdapter);
return view;