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Thread: Can't read really big files

  1. #1
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    Default Can't read really big files

    Hey,

    So basically I build a code to check lines on a .txt file and those likes compare a substring and change it to another saved string (always in the same position). Everything worked like a charm, no problem whatsoever, the messed up situation pops when I try to run the code on txt files with more than 2 million lines. This is definitely a problem because I need to run it on files with more than 10 million lines. What I tried to do was to save it on an ArrayList but it does not work, so Im lost here, been with this issue for more than 3 days, now Im getting to the point of dying. Here's the method call for the proccess:

          public void checaFechaSegunLugarUnico(String path, String archivo, int inicio, int fin) throws FileNotFoundException{
                  jTextArea2.setText("");    
                  try{
                  FileReader fstream = new FileReader(path);
                  //DataInputStream in = new DataInputStream(fstream);
                  BufferedReader br = new BufferedReader(fstream);
                  String strLine,primero, segundo, pivote,aux;
                  int i = 0;
                  ArrayList  almacem;
                  almacem = new ArrayList();
                  primero= "";
                  jTextArea2.append("Hola\n");
                  boolean bandera=true;
                  while ((strLine = br.readLine()) != null){
                      almacem.add(strLine);
                      /*if(strLine.length() < fin){
                      aux= strLine;
                      jTextArea2.append(aux+"\n");
                      }
                      else{
                      pivote = strLine.substring(inicio,fin);
                      if(pivote.equals(primero)) {
                              aux= strLine;
                          }
                      else{
                      if (bandera == true){
                          primero = pivote;
                          bandera = false;
                          aux=strLine;
                      }  else{
     
                          aux = strLine.substring(0, inicio)+primero+strLine.substring(fin);
                          //aux = strLine.replaceAll(pivote, primero);
                      }
                      }
     
                      jTextArea2.append(aux+"\n");
     
                  */}
                      jTextArea2.append("Salio\n");  
                      jTextArea2.append("Total leído: "+ almacem.size());
                  //}
                  /*SimpleDateFormat format = new SimpleDateFormat("yy-M-d");
                  jTextArea1.append(primero+"\n");
                  Date check = format.parse(primero);
                  Calendar calendar = Calendar.getInstance();
                  calendar.setTime(check);
                  int dia = Integer.parseInt(primero.substring(8));
                  int mes = calendar.get(Calendar.MONTH);
                  int año = calendar.get(Calendar.YEAR);
                  int ultDiaHab= obtenerUltimoDia(mes,año);
                  if(dia == ultDiaHab){
                      jTextArea1.append("La fecha capturada en el archivo "+archivo+" si concuerda con el último dia habil del mes\n");
                      crearArchivo(path,archivo);
                      jTextArea2.setText("");
                  }
                  else {
                      jTextArea1.append("La fecha capturada en el archivo "+archivo+" no concuerda con el último dia habil del mes\n");
                      jTextArea2.setText("");
                  }*/
     
                  }catch (Exception e){
     
                  }
     
       }

    Any help will be greatly appreciated.


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Can't read really big files

    it does not work,
    Please explain what "does not work" means. If you are getting error messages, copy and paste here the full text of the error message.
    If you don't understand my answer, don't ignore it, ask a question.

  3. The Following 2 Users Say Thank You to Norm For This Useful Post:

    curmudgeon (September 3rd, 2012), Yoso14 (September 3rd, 2012)

  4. #3
    Super Moderator curmudgeon's Avatar
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    Default Re: Can't read really big files

    I second what Norm says. Also this type of code makes me nervous:

                  }catch (Exception e){
     
                  }

    Please don't ignore exceptions. At least print a stacktrace:


                  }catch (Exception e){
                      e.printStackTrace();  // *** added *** 
                  }

  5. The Following 2 Users Say Thank You to curmudgeon For This Useful Post:

    Norm (September 3rd, 2012), Yoso14 (September 3rd, 2012)

  6. #4
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    Default Re: Can't read really big files

    First of all, thanks for your response. Now, Im supposed to get the size of the ArrayList almacem in jTextArea2 because I append the String there with jTextArea2.append("The size is " + almacem.size()) or at least I should get the first String that says jTextArea2.append("Salio\n"), but I aint getting any of those two in the Text Area, so my guessing is that the arrayList is not getting filled with the strLine values.

  7. #5
    Super Moderator Norm's Avatar
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    Default Re: Can't read really big files

    Add some println statements to print out the status of the execution as the lines are read.
    Print a message every nn (try different values for nn: 100 or 1000 etc) lines by define an int variable: cntr that is incremented by 1 for each line read and use the % to control when it prints:
    if(cntr++ % nn == 0) System.println("cntr=" + cntr);

    Was there an error message printed after you added the call to printStackTrace() to the catch block?
    If you don't understand my answer, don't ignore it, ask a question.

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