Question

我尝试使用ViewHolder实现ListView相对布局。在getView（）中，我遇到了NullReference。我在Stack Overflow上找到的示例之后对代码进行了建模。这是代码：

private ViewHolder mViewHolder;

public View getView(int position, View convertView, ViewGroup parent) {

    final ToDoItem toDoItem = mItems.get(position);

    if (convertView==null){
        mViewHolder = new ViewHolder();
        LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = inflater.inflate(R.layout.todo_item, parent, false);

        RelativeLayout itemLayout = (RelativeLayout) convertView.findViewById(R.id.RelativeLayout1);

        mViewHolder.tvTitle = (TextView) convertView.findViewById((R.id.title));
        mViewHolder.cbStatus = (CheckBox) convertView.findViewById(R.id.statusCheckBox);
        mViewHolder.tvPriority = (TextView) convertView.findViewById(R.id.priority);
        mViewHolder.tvDate = (TextView) convertView.findViewById(R.id.date);

        convertView.setTag(mViewHolder);
    }else{
        mViewHolder = (ViewHolder) convertView.getTag();
    }

    --->mViewHolder.tvTitle.setText(toDoItem.getTitle());
    mViewHolder.tvPriority.setText(toDoItem.getPriority().toString());
    mViewHolder.tvDate.setText(toDoItem.getDate().toString());
    mViewHolder.cbStatus.setChecked(false);

    if (toDoItem.getStatus().toString() == "DONE") mViewHolder.cbStatus.setChecked(true);


    final TextView titleView = mViewHolder.tvTitle;
    final CheckBox statusView = mViewHolder.cbStatus;
    final TextView priorityView = mViewHolder.tvPriority;
    final TextView dateView = mViewHolder.tvDate;

    itemLayout.addView(titleView);
    itemLayout.addView(statusView);
    itemLayout.addView(priorityView);
    itemLayout.addView(dateView);

    return convertView;

NullReference抛出

的右括号后面的行

if（convertView == null）

并标有----＆gt;

我尝试将不同的实体分配给ViewHolder，但收效甚微。我很感激任何人提供的任何帮助。提前谢谢！

Markb

Answer 1

toDoItem如果列表中的对象为空，也可以为null。

Android：ListView with RelativeLayout - ＆gt; NullReference

1 个答案: