Question

我正在创建动态视图。我想添加视图列表并删除它们onActivityResult。

但是当我将视图添加到列表中时，我在列表视图上得到NullPointerException。

我应该在列表视图中添加视图？

这是我的代码：

public class Mon extends Fragment {

    private FrameLayout fab;
    private EventTableHelper mDb;
    private Intent i;
    private ViewGroup dayplanView;
    private int minutesFrom,minutesTo;
    private List<EventData> events;
    private List<View> list;
    private EventData e;
    private LayoutInflater inflater;
    public  boolean editMode;
    private RelativeLayout container;
    RelativeLayout parent;
     View eventView;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        inflater = (LayoutInflater) getActivity().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_mon, container, false);

        fab = (FrameLayout) view.findViewById(R.id.main_fab);
        ImageButton imageButton = (ImageButton) view.findViewById(R.id.imgbtn_fab);
       imageButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                i = new Intent(getActivity(), AddEventActivity.class);

                editMode = false;
                i.putExtra("EditMode", editMode);
                startActivityForResult(i, 1);
            }
        });

        dayplanView = (ViewGroup) view.findViewById(R.id.hoursRelativeLayout);

        showEvents();

        return view;
    }

    private void createEvent(LayoutInflater inflater, ViewGroup dayplanView, int fromMinutes, int toMinutes, String title,String location,final int id) {

       eventView = inflater.inflate(R.layout.event_view, dayplanView, false);
        RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) eventView.getLayoutParams();

        container = (RelativeLayout) eventView.findViewById(R.id.container);
        TextView tvTitle = (TextView) eventView.findViewById(R.id.textViewTitle);


        if (tvTitle.getParent() != null)
           ((ViewGroup) tvTitle.getParent()).removeView(tvTitle);

        if(location.equals(""))
        {
            tvTitle.setText("Event : " + title);
        }
        else
        {
            tvTitle.setText("Event : " + title + " (At : " + location +")");
        }
        int distance = (toMinutes - fromMinutes);
        layoutParams.topMargin = dpToPixels(fromMinutes + 9);
        layoutParams.height = dpToPixels(distance);

        eventView.setLayoutParams(layoutParams);
        dayplanView.addView(eventView);
        container.addView(tvTitle);



        eventView.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                i = new Intent(getActivity(), AddEventActivity.class);
                editMode = true;
                i.putExtra("EditMode", editMode);
                i.putExtra("id", id);
                startActivityForResult(i, 1);

            }
        });
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        removeView();
        showEvents();
    }

    public void showEvents()
    {
        mDb = new EventTableHelper(getActivity());
        events = mDb.getAllEvents("Mon");

        for (EventData eventData : events) {

            int id = eventData.getId();
            String datefrom = eventData.getFromDate();

            if (datefrom != null) {
                String[] times = datefrom.substring(11, 16).split(":");
                minutesFrom = Integer.parseInt(times[0]) * 60 + Integer.parseInt(times[1]);
            }
            String title = eventData.getTitle();
            String location = eventData.getLocation();
            String dateTo = eventData.getToDate();

            if (dateTo != null) {
                //times = dateTo.substring(11,16).split(":");
                String[] times1 = dateTo.substring(11, 16).split(":");
                minutesTo = Integer.parseInt(times1[0]) * 60 + Integer.parseInt(times1[1]);
            }
            createEvent(inflater, dayplanView, minutesFrom, minutesTo, title, location, id);
            id++;

            list.add(eventView);
        }
    }

    public void removeView()
    {
        for(int i=0; i<list.size(); i++)
        {
            dayplanView.removeView(eventView);
        }
    }

    private int dpToPixels(int dp) {
        return (int) (dp * getResources().getDisplayMetrics().density);
    }

}

在list.add（eventview）获取异常; 请帮忙..

Answer 1

您的列表从未初始化，当您返回结果时，尝试将元素添加到空引用列表

<强>解决方案：

在onCreate执行：

list = new ArrayList<View>();

列表视图上的空指针异常

1 个答案: