無法下載圖像？

Question

Cursor appu=X.getsomething(); 

       if (appu.getCount() > 0) 
        { 
        if (appu.moveToFirst()) 
        { 
        do { 
          String uname = appu.getString(appu.getColumnIndex("content_id")); 
          String ax= appu.getString(appu.getColumnIndex("content")); 
          String unknown =url + ax; 
           t1.append("\n"); 
           t1.append(unknown); 
           //downloadimages(unknown,uname); 
         }while (appu.moveToNext()); 
        } 
        X.close(); 

這是我的代碼從數據庫中獲取一些結果，並由此結果我創建一個具有圖像的url，我想爲每個遊標結果下載該圖像，當我嘗試運行downloadimages()函數我的應用程序崩潰總是我不知道爲什麼......但是當我運行代碼沒有它，它運行完美。

downloadimages方法

 public void downloadimages(String url,String filename) 
     { 
      String ur1=url,v1=filename; 
      downloadManager = (DownloadManager)getSystemService(DOWNLOAD_SERVICE); 
       Uri Download_Uri = Uri.parse(ur1); 
       DownloadManager.Request request = new DownloadManager.Request(Download_Uri); 
       request.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI | DownloadManager.Request.NETWORK_MOBILE); 
       request.setAllowedOverRoaming(false); 
      request.setDescription("Android Data download using DownloadManager."); 
      request.setDestinationInExternalFilesDir(getApplicationContext(),Environment.DIRECTORY_DOWNLOADS,v1 + ".jpg"); 
       downloadManager.enqueue(request);  

     } 

，請告訴我，我做錯了什麼???

Cursor appu=X.getsomething(); 

       if (appu.getCount() > 0) 
        { 
        if (appu.moveToFirst()) 
        { 
        do { 
          String uname = appu.getString(appu.getColumnIndex("content_id")); 
          String ax= appu.getString(appu.getColumnIndex("content")); 
          imageid.add(uname); 
          String unknown =url + ax; 
          imagepath.add(unknown); 
          // t1.append("\n"); 
           //t1.append(unknown); 
         }while (appu.moveToNext()); 
        } 
        X.close(); 
        }} 
      this.getitdone(); 
      } 


     public void getitdone() 
     { 
      int b=imagepath.size(); 

      for(int i=1;i<=b;i++) 
      { 
       String extra=imagepath.get(i).toString(); 
       String extra2=imageid.get(i).toString(); 
       downloadimages(extra,extra2); 
      } 

     } 

現在我做這種方式，它是可以正常使用

Answer 1

這是普拉莫德如何解決該問題：

Cursor appu=X.getsomething(); 

      if (appu.getCount() > 0) 
       { 
       if (appu.moveToFirst()) 
       { 
       do { 
         String uname = appu.getString(appu.getColumnIndex("content_id")); 
         String ax= appu.getString(appu.getColumnIndex("content")); 
         imageid.add(uname); 
         String unknown =url + ax; 
         imagepath.add(unknown); 
         // t1.append("\n"); 
          //t1.append(unknown); 
        }while (appu.moveToNext()); 
       } 
       X.close(); 
       }} 
     this.getitdone(); 
     } 


    public void getitdone() 
    { 
     int b=imagepath.size(); 

     for(int i=1;i<=b;i++) 
     { 
      String extra=imagepath.get(i).toString(); 
      String extra2=imageid.get(i).toString(); 
      downloadimages(extra,extra2); 
     } 

    }