Question

我正在尝试动态地将TableLayout添加到片段内的LinearLayout中。

以下代码：

public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState){
        View rootview = inflater.inflate(R.layout.dashboard_fragment, container, false);
        dash_board = (LinearLayout) rootview.findViewById(R.layout.dashboard_fragment);
        table = new TableLayout(getActivity());
        TableRow tr_header = new TableRow(getActivity());
        TextView Name = new TextView(getActivity());

        Name.setText("Name");
        LayoutParams Name_params =  new LayoutParams();
        Name_params.width= 100;

        Name.setLayoutParams(Name_params);
        Name.setPadding(2, 0, 2, 2);

        tr_header.addView(Name);

        TextView Points = new TextView(getActivity());

        Points.setText("Points");
        LayoutParams point_params =  new LayoutParams();
        point_params.width= 100;

        Points.setLayoutParams(point_params);
        Points.setPadding(2, 0, 2, 2);

        tr_header.addView(Points);

        table.addView(tr_header);

        dash_board.addView(table);

        return rootview;
    }

但是在将仪表板添加到仪表板布局（dash_board.addView（table）;）时，我得到的是NullPointerException。

问题是什么？

Answer 1

实际上在rootView中没有dashboard_fragment作为ViewGroup，因为rootView是一个非常明显的dashboard_fragment作为ViewGroup。所以这两行代码是异常的原因：

查看rootview =   inflater.inflate（R.layout.dashboard_fragment，container，false）;

dash_board =   （的LinearLayout）rootview.findViewById（R.layout.dashboard_fragment）;

如果您这样做，实际上逻辑是正确的：

查看rootview =   inflater.inflate（R.layout.dashboard_fragment，container，false）;

dash_board =   （LinearLayout）rootView;

这是此过程最简单的形式：

dash_board =（LinearLayout）inflater.inflate（R.layout.dashboard_fragment，container，false）;

Answer 2

而不是这个

View rootview = inflater.inflate(R.layout.dashboard_fragment, container, false);
    dash_board = (LinearLayout) rootview.findViewById(R.layout.dashboard_fragment);

应该是

LinearLayout dash_board = (LinearLayout)inflater.inflate(R.layout.dashboard_fragment,              container, false);

在动态添加片段中的视图时出现NullPointerException

2 个答案: