Question

Hi I am writting an android application to get information from a url and show it in a ListView. All are working well. but it takes long time to show the View because i read the file from url on onCreate() method.

1. I want read from the URL asynchronously, so view response time will not harmed.

2. Am I using the ProgressBar correctly?.

   public class cseWatch extends Activity  {
       TextView txt1 ;
       Button btnBack;
       ListView listView1;
       /** Called when the activity is first created. */
       @Override
   
       public void onCreate(Bundle savedInstanceState) {
   
           super.onCreate(savedInstanceState);
           setContentView(R.layout.searchresult);
   
           Button btnBack=(Button) findViewById(R.id.btn_bck);
           btnBack.setOnClickListener(new View.OnClickListener() {
   
               @Override
               public void onClick(View v) {
                   // TODO Auto-generated method stub
                   Intent MyIntent1 = new Intent(v.getContext(),cseWatchMain.class);
                   startActivity(MyIntent1);
               }
           });
   
           ArrayList<SearchResults> searchResults = GetSearchResults();
   
           //after loaded result hide progress bar
           ProgressBar pb = (ProgressBar) findViewById(R.id.progressBar1);
           pb.setVisibility(View.INVISIBLE);
   
           final ListView lv = (ListView) findViewById(R.id.listView1);
           lv.setAdapter(new MyCustomBaseAdapter(cseWatch.this, searchResults));
   
           lv.setOnItemClickListener(new OnItemClickListener() {
               @Override
               public void onItemClick(AdapterView<?> a, View v, int position, long id) {
                   Object o = lv.getItemAtPosition(position);
                   SearchResults fullObject = (SearchResults)o;
                   Toast.makeText(cseWatch.this, "You have chosen: " + " " + fullObject.getName(), Toast.LENGTH_LONG).show();
               }
           });
   
   
       }//end of onCreate
   
   
   private ArrayList<SearchResults> GetSearchResults(){
       ArrayList<SearchResults> results = new ArrayList<SearchResults>();
   
       SearchResults sr;
       InputStream in;
       try{
           txt1 = (TextView) findViewById(R.id.txtDisplay);
           txt1.setText("Sending request...");
           DefaultHttpClient httpclient = new DefaultHttpClient();
           HttpGet httpget = new HttpGet("http://www.myurl?reportType=CSV");
           HttpResponse response = httpclient.execute(httpget);
           in = response.getEntity().getContent();
   
           txt1.setText("parsing CSV...");
   
   
           BufferedReader reader = new BufferedReader(new InputStreamReader(in));
               try {
                   String line;
                   reader.readLine(); //IGNORE FIRST LINE
   
                   while ((line = reader.readLine()) != null) {
                        String[] RowData = line.split(",");
                        sr = new SearchResults();
   
                        String precent = String.format("%.2g%n",Double.parseDouble(RowData[12])).trim();
   
                        double chng=Double.parseDouble(RowData[11]);
                        String c;
                        if(chng > 0){
                            sr.setLine2Color(Color.GREEN);
                            c="▲";
                        }else if(chng < 0){
                            sr.setLine2Color(Color.rgb(255, 0, 14));
                            c="▼";
                        }else{
                            sr.setLine2Color(Color.rgb(2, 159, 223));
                            c="-";
                        }
   
                        sr.setName(c+RowData[2]+"-"+RowData[1]);
   
   
                        DecimalFormat fmt = new DecimalFormat("###,###,###,###.##");
                        String price = fmt.format(Double.parseDouble(RowData[6])).trim();
                        String tradevol = fmt.format(Double.parseDouble(RowData[8])).trim();
   
                        sr.setLine1("PRICE: Rs."+price+" TRADE VOL:"+tradevol);
                        sr.setLine2("CHANGE:"+c+RowData[11]+" ("+precent+"%)");
                        results.add(sr);
                        txt1.setText("Loaded...");
                       // do something with "data" and "value"
                   }
               }
               catch (IOException ex) {
                   Log.i("Error:IO",ex.getMessage());
               }
               finally {
                   try {
                       in.close();
                   }
                   catch (IOException e) {
                       Log.i("Error:Close",e.getMessage());
                   }
               }
       }catch(Exception e){
           Log.i("Error:",e.getMessage());
           new AlertDialog.Builder(cseWatch.this).setTitle("Watch out!").setMessage(e.getMessage()).setNeutralButton("Close", null).show();  
       }
   
       return results;
      }
   
   } 
   

Answer 1

AsyncTask should be used to move the heavylifting away from UI thread. http://developer.android.com/reference/android/os/AsyncTask.html