Android ProgressDialog不顯示

Question

我創建了一個AlertDialog以讓用戶選擇是否從服務器下載某些東西。

如果用戶選擇下載，則AlertDialog被解僱，並且出現連接到AsyncTask的ProgressDialog。

ProgressDialog從不顯示。 AlertDialog的「ok」按鈕保持選中狀態，直至AsyncTask的操作結束。

如果我在代碼中「評論」AsyncTask操作，AlertDialog被正確解除，並且ProgressDialog顯示出來。

我還沒有嘗試在真實設備上的應用程序，但只有模擬器。

這是問題所在？

Answer 1

試試這個代碼，這可能使用AlertDialog肯定按鈕幫助您在AsyncTask例如

private class allinfo extends AsyncTask<String, Void, JSONObject> { 
     private ProgressDialog dialog; 

     protected void onPreExecute(){ 
      dialog = ProgressDialog.show(collection.this, "Loading", "Loading. Please wait...", true,false); 
     } 

     @Override 
     protected JSONObject doInBackground(String... arg0) { 
      // TODO Auto-generated method stub 

      return json; 
     } 
     protected void onPostExecute(JSONObject json) 
     { 
      dialog.dismiss(); 
      info(json); 
     } 

    } 

Answer 2

ProgressDialog實現：

public class MainActivity extends Activity { 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main_layout); 

     AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this); 
     // set title 
     alertDialogBuilder.setTitle("Your Title"); 
     // set dialog message 
     alertDialogBuilder 
     .setMessage("Click yes to go to AsyncTask!") 
     .setPositiveButton("Yes",new DialogInterface.OnClickListener() { 
      public void onClick(DialogInterface dialog,int id) { 
       new MyAsyncTaskClass().execute(); 
      } 
     }) 
     .setNegativeButton("No",new DialogInterface.OnClickListener() { 
      public void onClick(DialogInterface dialog,int id) { 
       // if this button is clicked, just close 
       // the dialog box and do nothing 
       dialog.cancel(); 
      } 
     }); 
     // create alert dialog 
     AlertDialog alertDialog = alertDialogBuilder.create(); 
     // show it 
     alertDialog.show(); 

    } 

    // Here is the start of the AsyncTask  
    class MyAsyncTaskClass extends AsyncTask<String, String, Void> { 

     private ProgressDialog progressDialog = new ProgressDialog(MainActivity.this); 

     protected void onPreExecute() { 
      progressDialog.setMessage("Dialog Message"); 
      progressDialog.show(); 
      progressDialog.setCanceledOnTouchOutside(false); 
     } 

     @Override 
     protected Void doInBackground(String... params) { 
      // TODO stuff 
     } 

     protected void onPostExecute(Void v) { 
      this.progressDialog.dismiss(); 
     } 
    } 
} 

Answer 3

final AlertDialog d = new AlertDialog.Builder(youclassname.this) 
     .setView(input) 
     .setTitle(R.string.message) 
     .setPositiveButton(android.R.string.ok, 
       new Dialog.OnClickListener() { 
        public void onClick(DialogInterface d, int which) { 
         //Do nothing here. We override the onclick 
        } 
       }) 
     .setNegativeButton(android.R.string.cancel, null) 
     .create(); 

d.setOnShowListener(new DialogInterface.OnShowListener() { 

    public void onShow(DialogInterface dialog) { 

     Button b = d.getButton(AlertDialog.BUTTON_POSITIVE); 
     b.setOnClickListener(new View.OnClickListener() { 

      public void onClick(View view) { 

         startDownload();//begin downloading 
        d.dismiss(); 

      } 
     }); 
    } 
}); 
d.show(); 

這裏是startDownload一部分。

private void startDownload() { 
     String url ="file download link"; 
     Toast.makeText(dwn.this, url,Toast.LENGTH_LONG).show(); 
     new DownloadFileAsync().execute(url); 
    } 

這裏是的AsyncTask

class DownloadFileAsync extends AsyncTask<String, String, String> { 

    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     showDialog(DIALOG_DOWNLOAD_PROGRESS); 
    } 

    @Override 
    protected String doInBackground(String... aurl) { 
     int count; 

    try { 

    URL url = new URL(aurl[0]); 
    URLConnection conexion = url.openConnection(); 
    conexion.connect(); 

    int lenghtOfFile = conexion.getContentLength(); 
    Log.d("ANDRO_ASYNC", "Lenght of file: " + lenghtOfFile); 

    InputStream input = new BufferedInputStream(url.openStream()); 
    OutputStream output = new FileOutputStream("/sdcard/file.type"); 

    byte data[] = new byte[1024]; 

    long total = 0; 

     while ((count = input.read(data)) != -1) { 
      total += count; 
      publishProgress(""+(int)((total*100)/lenghtOfFile)); 
      output.write(data, 0, count); 
     } 

     output.flush(); 
     output.close(); 
     input.close(); 






      } 
      catch (Exception e) { 
       // TODO Auto-generated catch block 

      } 

    return null; 

    } 
    protected void onProgressUpdate(String... progress) { 
     Log.d("ANDRO_ASYNC",progress[0]); 
     mProgressDialog.setProgress(Integer.parseInt(progress[0])); 
    } 

    @Override 
    protected void onPostExecute(String unused) { 
     dismissDialog(DIALOG_DOWNLOAD_PROGRESS); 
    } 
} 

這裏是進度對話框

@Override 
    protected Dialog onCreateDialog(int id) { 
     switch (id) { 
     case DIALOG_DOWNLOAD_PROGRESS: 
      mProgressDialog = new ProgressDialog(this); 
      mProgressDialog.setMessage("Downloading PDF file"); 
      mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL); 
      mProgressDialog.setCancelable(false); 
      mProgressDialog.show(); 
      return mProgressDialog; 
     default: 
      return null; 
     } 
    }