hi all,
I am trying to make a program called "Duplicated" which reads thousand of strings(barcodes), then it checks whether a barcode is written more than once or not,
if yes the programm should print out the list of all barcodes which occurences it is more than once.

Tecnicaly, since I don't know exactly how many are the barcodes I use a vector(it's called "primo") instead of an array, then I start to a nested cycle to see the
occurences of a single barcode if it is more than once it will store it in another vector called "secondo". At the end the programm should print out all the elements of
the vector "secondo".

Well, the strange thing, it is that the program reads the barcodes, then store them into "primo" but it's not able to store into "secondo".
Why???




Thanks in advance

P.S. I used also a file already made to help me for semplify the syntax of the streaming code(it is called Text.java). Please before running the file Duplicated.class, create a file called barcode.txt in which just made up some barcodes such as: "FOD 4533" and so forth.

----------------------------------------------------------------------
import java.io.*;
import java.util.*;

public class Duplicated{
public static void main(String[]args) throws IOException{


Vector primo=new Vector();
Vector secondo=new Vector();


BufferedReader fin=Text.open("barcode.txt");


try {
for( ; ; ){
String number=(Text.readString(fin));
  primo.add(number);

}
}

catch(EOFException e){




System.out.println("Ok strings imported !");


for(int i=0; i<primo.size(); i++)
System.out.println((String)primo.get(i));
}


// **compare whether the elements of primo are duplicated if yes store it into secondo

// from the instruction below I can see that the initial size as expected is zero
System.out.println(" the size of the vector secondo is: "+secondo.size());

     for(int i=0; i<primo.size(); i++){
      int a=0;
      for(int j=0; j<primo.size(); j++){
      if ((String)primo.get(i)==(String)primo.get(j))
           {a++; }}
      if (a>1)
          {secondo.add((String)primo.get(i));}
        }

// now print out all the duplicated barcodes

//I find out that the size of the vector secondo is still zero
System.out.println(" the size of the vector secondo is still : "+secondo.size());
for(int i=0; i<secondo.size(); i++)
  System.out.println((String)secondo.get(i));
//**
  }
}

----------------------------------------------------------------------


import java.io.*;
import java.util.*;
import java.text.*;

public class Text {

  public Text () {};

  /* The All New Famous Text class by J M Bishop Aug 1996
   * revised for Java 1.1 by Alwyn Moolman Aug 1997
   * revised for efficiency by J M Bishop Dec 1997
   *
   * Provides simple input from the keyboard and files.
   * Now also has simple output formatting methods
   * and file opening facilities.
   *
   * public static void prompt (String s)
   * public static int readInt (BufferedReader in)
   * public static double readDouble (BufferedReader in)
   * public static String readString (BufferedReader in)
   * public static char readChar (BufferedReader in)
   * public static String writeInt (int number, int align)
   * public static String writeDouble
                   (double number, int align, int frac)
   * public static BufferedReader open (InputStream in)
   * public static BufferedReader open (String filename)
   * public static PrintWriter create (String filename)
   *
   * January 2001
   * Now local to the javagently package as it has been
   * superceded for program development by the Stream class.
   * It is still needed by Graph and Display.
   */

  private static StringTokenizer T;
  private static String S;

  public static BufferedReader open (InputStream in) {
    return new BufferedReader(new InputStreamReader(in));
  }

  public static BufferedReader open (String filename)
    throws FileNotFoundException {
    return new BufferedReader (new FileReader (filename));
  }

  public static PrintWriter create
     (String filename) throws IOException {
    return new PrintWriter (new FileWriter (filename));
  }

  public static void prompt (String s) {
    System.out.print(s + " ");
    System.out.flush();
  }

  public static int readInt (BufferedReader in) throws IOException {
      if (T==null) refresh(in);
      while (true) {
        try {
          return Integer.parseInt(T.nextToken());
        }
        catch (NoSuchElementException e1) {
          refresh (in);
        }
        catch (NumberFormatException e2) {
          System.out.println("Error in number, try again.");
        }
      }
   }

 public static char readChar (BufferedReader in) throws IOException {
      if (T==null) refresh(in);
      while (true) {
        try {
          return T.nextToken().trim().charAt(0);
        }
        catch (NoSuchElementException e1) {
          refresh (in);
        }
      }
   }

 public static double readDouble (BufferedReader in) throws IOException {
      if (T==null) refresh(in);
      while (true) {
        try {
          String item = T.nextToken();
          return Double.valueOf(item.trim()).doubleValue();
        }
        catch (NoSuchElementException e1) {
          refresh (in);
        }
        catch (NumberFormatException e2) {
          System.out.println("Error in number, try again.");
        }
      }
   }

  public static String readString (BufferedReader in) throws IOException {
    if (T==null) refresh (in);
    while (true) {
      try {
        return T.nextToken();
      }
      catch (NoSuchElementException e1) {
        refresh (in);
      }
    }
  }

  private static void refresh (BufferedReader in) throws IOException {
    S = in.readLine ();
    if (S==null) throw new EOFException();
    T = new StringTokenizer (S);
  }

  // Write methods
  // -------------

  private static DecimalFormat N = new DecimalFormat();
  private static final String spaces = " ";

  public static String writeDouble (double number, int align, int frac) {
    N.setGroupingUsed(false);
    N.setMaximumFractionDigits(frac);
    N.setMinimumFractionDigits(frac);
    String num = N.format(number);
    if (num.length() < align)
      num = spaces.substring(0,align-num.length()) + num;
    return num;
  }

  public static String writeInt (int number, int align) {
    N.setGroupingUsed(false);
    N.setMaximumFractionDigits(0);
    String num = N.format(number);
    if (num.length() < align)
      num = spaces.substring(0,align-num.length()) + num;
    return num;

  }
}