我很想知道,在不造成整个清单重载的情况下,能否在清单中添加一个项目。
我有一份由Sapter-derd ListView改编机,当基本模型添加新的内容时,我打电话通知DataSetChanged(),触发了名单的重新载荷。
清单中的内容有图像,根据内容,这些图像具有动态负荷。 问题在于,如果在重载时发出意见,改换字 用于再利用的观察参数来自以前不同的位置,因此,图像也必须重载,造成一种相当模糊的连接。
因此,如果我最后增加一个项目(这将是增加新项目的唯一途径)的话,那么
我很想知道,在不造成整个清单重载的情况下,能否在清单中添加一个项目。
我有一份由Sapter-derd ListView改编机,当基本模型添加新的内容时,我打电话通知DataSetChanged(),触发了名单的重新载荷。
清单中的内容有图像,根据内容,这些图像具有动态负荷。 问题在于,如果在重载时发出意见,改换字 用于再利用的观察参数来自以前不同的位置,因此,图像也必须重载,造成一种相当模糊的连接。
因此,如果我最后增加一个项目(这将是增加新项目的唯一途径)的话,那么
No buddy its not possible in android that u can add an item without refresh the list because when u add an item it changes the height of list view.See the below link,Romain Guy said the same thing in it.
do this instead of calling notifyDataSetChanged():
int firstVisiblePosition = getFirstVisiblePosition();
View view = getChildAt(0);
int distFromTop = (view == null) ? 0 : view.getTop();
setSelectionFromTop(firstVisiblePosition, distFromTop);
这样做也是可能的。
越权越权,越权越权越权,越权越权越权。
例如:
public class custom_row extends ArrayAdapter<String> {
String newItem = "";
Boolean doRefresh = true;
public custom_row(Context context, int resource, ArrayList<String> objects) {
super(context, resource, objects);
}
public custom_row(Context context, int resource, String[] objects) {
super(context, resource, objects);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
String itemValue = getItem(position);
if (doRefresh == false && itemValue != newItem) {
return convertView;
}
LayoutInflater inflater = LayoutInflater.from(getContext());
View customView = inflater.inflate(R.layout.customr_row, parent, false);
ImageView myImageView = (ImageView) customView.findViewById(R.id.imageView);
String url = "https://urltoimage/image.jpg";
(new DownloadImageTask(myImageView)).execute(url);
TextView myTextView = (TextView) customView.findViewById(R.id.myCustomText);
myTextView.setText(itemValue);
return customView;
}
public void addNewItemToList(String item) {
this.newItem = item;
this.doRefresh = false;
add(item);
}
private class DownloadImageTask extends AsyncTask<String, Integer, Bitmap>{
private ImageView mImageView;
public DownloadImageTask(ImageView imageView) {
this.mImageView = imageView;
}
@Override
protected Bitmap doInBackground(String... params) {
URL url = null;
Bitmap bmp = null;
try {
url = new URL(params[0]);
} catch (MalformedURLException e) {
e.printStackTrace();
}
try {
InputStream stream = url.openStream();
bmp = BitmapFactory.decodeStream(stream);
} catch (IOException e) {
e.printStackTrace();
}
return bmp;
}
@Override
protected void onPostExecute(Bitmap bmp) {
this.mImageView.setImageBitmap(bmp);
}
}
}
它第一次装上所有物品,图像由Aync透镜猛装。 该法典的下列部分在方法上使该清单无法完全更新,从而防止图像的链接:
String itemValue = getItem(position);
if (doRefresh == false && itemValue != newItem) {
return convertView;
}
名单上增列一个新项目时,ArrayAdapter将再次通过名单。 仅检查目前情况下的项目是否是新增列的项目。 否则,改换者将返回 旧观点或将物品装上其他观点,并回复习俗观点。
If you set your adapter to have stable ids then it should prevent getView(...)
from being called for the views that were already visible before calling notifyDataSetChanged()
. This can be done by overriding hasStableIds()
so that it returns true
and then making sure that your implementation of getItemId(...)
is actually returning a stable and unique id.
@Override
public long getItemId(int position) {
//you can use position if you only append items, otherwise you will
//need to handle the ids on your own and keep them stable and unique
final long id = position;
return id;
}
@Override
public final boolean hasStableIds() {
return true;
}
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