android - 让表在 fragment 中，错误是在空对象引用上

Question

代码如下:

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);
    }
}

这里是错误:

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。我真的很期待你的帮助。

Answer 1

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

这一行有一些问题，所以 tableFixHeaders 实际上是空的。
您应该先膨胀 View ，然后从膨胀的 View 中找到 subview 。

在您的 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;