我有下面的代码，我得到了一个空指针异常(见下文(。我想检索视图持有者指向的用户名。我甚至试图通过视图(v(本身检索它，但我得到了同样的例外。我不明白为什么这个值为空。
public class ContactAdapter extends BaseAdapter {
private Context mContext;
public ContactAdapter(Context context) {
mContext = context;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
convertView = LayoutInflater.from(mContext).inflate(R.layout.item_contact, null);
holder = new ViewHolder(convertView);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
ViewHolder vv = (ViewHolder)v.getTag();
TextView tv = (TextView) vv.userName.getText(); // Exception here - Line 120
}catch(Exception xx){
}
}
});
}
private class ViewHolder {
TextView userName;
ImageView add, delete, block,profImage;
public ViewHolder(View view) {
userName = (TextView) view.findViewById(R.id.user_name);
add = (ImageView) view.findViewById(R.id.add);
delete = (ImageView) view.findViewById(R.id.delete);
block = (ImageView) view.findViewById(R.id.block);
profImage = (ImageView) view.findViewById(R.id.profile_image);
}
}
例外情况如下：在此处输入图像描述
view.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
ViewHolder vv = (ViewHolder)v.getTag();
TextView tv = (TextView) vv.userName.getText();
}catch(Exception xx){
}
}
});
你在viewholder构造函数中尝试过吗。。。我认为你得到了空指针异常，因为你在holder上设置了点击列表。删除
替换"ViewHolder holder；"由"最终ViewHolder持有者；"在onClick方法中，只需执行"holder.userName.getText(("等操作即可访问视图。
试试这个，
ViewHolder vv = (ViewHolder)convertView.getTag();
holder.delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
try {
ViewHolder vv = (ViewHolder)v.getTag();
TextView tv = (TextView) vv.userName.getText(); // Exception here - Line 120
}catch(Exception xx){
}
}
});
您为convertView设置了标记，但您的getTag()来自convertView的子级。所以它将是null
修复它：
将ViewHolder更改为最终
最终ViewHolder持有者；
直接从持有者获取文本
holder.delete.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { try { TextView tv = (TextView) holder.userName.getText(); }catch(Exception xx){ } } });