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android ExpandableListView - NullPointerException

转载 作者:行者123 更新时间:2023-11-30 04:15:40 26 4
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Blockquote

我在 android 中使用 ExpandableListView

这是适配器类中getChildView的代码:

    @Override
public View getChildView(int groupPosition, int childPosition,
boolean isLastChild, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {

LayoutInflater inflater = (LayoutInflater) myContext
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = inflater.inflate(R.layout.childrow, null);
holder = new ViewHolder();

holder.tv = (TextView) convertView
.findViewById(R.id.textView1);
// I added this line of code
holder.stop = (Button) convertView.findViewById(R.id.button3);

holder.position = groupPosition;
convertView.setTag(holder);
holder.stop.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {

ViewHolder holder = new ViewHolder();
holder = (ViewHolder) v.getTag();

int position = 0;

position = holder.position; ************* here

System.out.println("coolapse tag " + position);

expList.collapseGroup(position);


}
});

} else {
holder = (ViewHolder) convertView.getTag();
}

return convertView;
}

它在 ** 标记的行中给出 NullPointerException有什么问题吗?

最佳答案

什么是 holder.stopholder.stop不是您设置标签的 View ,所以当您尝试执行 v.getTag() 时,你在 holder 中得到一个空值(顺便说一句,我没有看到 holder.stop 被初始化)。不确定你到底要做什么,但解决它的方法是将支架设置在 stop 上也可以查看:

convertView.setTag(holder);
holder.stop.setTag(holder);
holder.stop.setOnClickListener(....

关于android ExpandableListView - NullPointerException,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10065100/

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