更改与AsyncTask的单个项目的ListView android的 [英] change single item listview android with asynctask
问题描述
我正在学习如何改变单一的项目列表视图定制的Android与AsyncTask的，我跟着的本教程。
I'm learning how to change single item custom listview android with AsyncTask, I've followed this tutorial.
但它似乎并没有在我的列表视图工作。
but it's seem not work in my listview.
这是我的code
private class ViewHolder {
public ImageButton favorite;
public TextView jmlh_favorite;
protected int position;
}
public View getView(final int position, View convertView, ViewGroup parent) {
View vi = convertView;
final ViewHolder holder;
if (convertView == null) {
vi = inflater.inflate(R.layout.laporan_list_item, null);
holder = new ViewHolder();
holder.jmlh_favorite = (TextView)vi.findViewById(R.id.jmlh_favorite);
holder.favorite = (ImageButton)vi.findViewById(R.id.favorite);
vi.setTag(holder);
} else {
holder = (ViewHolder) vi.getTag();
}
holder.favorite.setOnClickListener(new android.view.View.OnClickListener() {
@Override
public void onClick(View v) {
holder.position = position;
position_change=position;
String varid_laporan = holder.id_laporan.getText().toString();
String var_kat_favorite = holder.kat_favorite.getText().toString();
url = "http://xxxx.com/android/upload_image/favorite_laporan.php?kat="+var_kat_favorite+"&id_laporan="+varid_laporan+"&uid="+URLEncoder.encode(uid);
grabURL(url,position,holder);
}
});
return vi;
}
public void grabURL(String url, int position,ViewHolder holder) {
Log.v("Android Spinner JSON Data Activity", url);
mTask = new GrabURL(position, holder).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, url);
}
private class GrabURL extends AsyncTask<String, Void, String> {
private static final int REGISTRATION_TIMEOUT = 3 * 1000;
private static final int WAIT_TIMEOUT = 30 * 1000;
private final HttpClient httpclient = new DefaultHttpClient();
final HttpParams params = httpclient.getParams();
HttpResponse response;
private String content = null;
private boolean error = false;
private ProgressDialog dialog = new ProgressDialog(activity);
private int mPosition;
private ViewHolder mHolder;
public GrabURL(int position, ViewHolder holder) {
mPosition = position;
mHolder = holder;
}
protected void onPreExecute() {
dialog.setMessage("Getting your data... Please wait...");
}
protected String doInBackground(String... urls) {
String URL = null;
try {
URL = urls[0];
HttpConnectionParams.setConnectionTimeout(params, REGISTRATION_TIMEOUT);
HttpConnectionParams.setSoTimeout(params, WAIT_TIMEOUT);
ConnManagerParams.setTimeout(params, WAIT_TIMEOUT);
HttpPost httpPost = new HttpPost(URL);
response = httpclient.execute(httpPost);
StatusLine statusLine = response.getStatusLine();
if (statusLine.getStatusCode() == HttpStatus.SC_OK) {
ByteArrayOutputStream out = new ByteArrayOutputStream();
response.getEntity().writeTo(out);
out.close();
content = out.toString();
} else {
//Closes the connection.
Log.w("HTTP1:",statusLine.getReasonPhrase());
response.getEntity().getContent().close();
throw new IOException(statusLine.getReasonPhrase());
}
} catch (ClientProtocolException e) {
Log.w("HTTP2:",e );
content = e.getMessage();
error = true;
cancel(true);
} catch (IOException e) {
Log.w("HTTP3:",e );
content = e.getMessage();
error = true;
cancel(true);
} catch (Exception e) {
Log.w("HTTP4:",e );
content = e.getMessage();
error = true;
cancel(true);
}
return content;
}
protected void onCancelled() {
mTask.cancel(true);
statusKoneksi();
}
protected void onPostExecute(String content) {
if (error) {
mTask.cancel(true);
statusKoneksi();
} else {
displaylaporanList(content,mPosition,mHolder);
mTask.cancel(true);
}
}
}
private void displaylaporanList(String response, int mPosition, ViewHolder mHolder){
JSONObject json = null;
try {
json = new JSONObject(response);
laporanListObj = json.getJSONArray(ContentLaporanActivity.TAG_FAVORITE_LAPORAN);
int Jumlah_list_Data = laporanListObj.length();
if (Jumlah_list_Data== 0) {
} else {
JSONObject c = laporanListObj.getJSONObject(0);
String jumlah_favorite = c.getString(ContentLaporanActivity.TAG_BANYAK_FAVORITE_LAPORAN);
String status_favorite = c.getString(ContentLaporanActivity.TAG_STATUS_FAVORITE);
if (mHolder.position == mPosition) {
mHolder.jmlh_favorite.setText(status_favorite);
}
}
notifyDataSetChanged();
} catch (JSONException e) {
e.printStackTrace();
}
}
void statusKoneksi(){
Toast.makeText(activity, "gagal", Toast.LENGTH_SHORT).show();
}
和这部分，我想的setText时方法结果的AsyncTask displaylaporanList（），但它不是设置的文本。
and this part where I want to setText when result asynctask in method displaylaporanList(), but it's not set Text.
if (mHolder.position == mPosition) {
mHolder.jmlh_favorite.setText(status_favorite);
}
如何更新文本？
推荐答案
的逻辑问题与code是以下几点：你不应该 getView（）的。 ViewHolder 是只是关于名单的性能更好，不应该被用来作为参考列出的任何时刻项目。
The logic issue with your code is the following: You shouldn't update ViewHolder outside of getView(). ViewHolder is just about making list performance better and shouldn't be used as reference to list items in any moment of time.
在你的情况下，要解决这个问题你应该叫 holder.jmlh_favorite.setText（status_favorite）在 getView（）（如商店位置和文字的地方）。从 displaylaporanList（）你只需要调用 notifyDataSetChanged（）来通知该数据已更改，并列出适配器项应当被更新。另外，请参阅本届/ O 的约列表视图的更多细节。
In your case, to fix the issue You should call holder.jmlh_favorite.setText(status_favorite) inside getView() (e.g. store position and text somewhere). From displaylaporanList() You just need to call notifyDataSetChanged() to notify the Adapter that the data has been changed and list items should be updated. Also, refer to this session from Google I/O for more details about ListViews.
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