Android 为什么示例代码使用getTag();
下面的示例代码来自网站,我认为holder=(ViewHolder)convertView.getTag()应该是holder=(ViewHolder)convertView,对吗?谢谢Android 为什么示例代码使用getTag();,android,Android,下面的示例代码来自网站,我认为holder=(ViewHolder)convertView.getTag()应该是holder=(ViewHolder)convertView,对吗?谢谢 public class ImageAdapter extends BaseAdapter { private LayoutInflater mInflater; public ImageAdapter() { mInflater = (Layo
public class ImageAdapter extends BaseAdapter {
private LayoutInflater mInflater;
public ImageAdapter() {
mInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
public int getCount() {
return count;
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder;
if (convertView == null) {
holder = new ViewHolder();
convertView = mInflater.inflate(R.layout.galleryitem, null);
holder.imageview = (ImageView) convertView.findViewById(R.id.thumbImage);
holder.checkbox = (CheckBox) convertView.findViewById(R.id.itemCheckBox);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.checkbox.setId(position);
holder.imageview.setId(position);
holder.checkbox.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
CheckBox cb = (CheckBox) v;
int id = cb.getId();
if (thumbnailsselection[id]) {
cb.setChecked(false);
thumbnailsselection[id] = false;
} else {
cb.setChecked(true);
thumbnailsselection[id] = true;
}
}
});
holder.imageview.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
int id = v.getId();
Intent intent = new Intent();
intent.setAction(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.parse("file://" + arrPath[id]),
"image/*");
startActivity(intent);
}
});
holder.imageview.setImageBitmap(thumbnails[position]);
holder.checkbox.setChecked(thumbnailsselection[position]);
holder.id = position;
return convertView;
}
}
class ViewHolder {
ImageView imageview;
CheckBox checkbox;
int id;
}
}
我认为holder=(ViewHolder)convertView.getTag()应该是holder=
(视图持有人)转换视图
既然
ViewHolder
不是视图
演员阵容如何运作?将ViewHolder
对象设置为convertView
的标记,并在每次调用getView
时检索它,以避免查找视图组件(您的ImageView
和复选框
)。这样可以避免在滚动ListView
时调用findViewById()
,您的意思是在这种情况下我们应该使用holder=(ViewHolder)convertView.getTag()吗