How To Modify Text So That It Doesn't Contain Two Equal Numbers

I would like to create a program that takes some files and modifies them in this way: The files should contain text formatted in this way:

##############
#various comments#
##############
something{
identifier=1234
anotherIdentifier=1235
anotherOne=12345
//and so on...
}//I need only this
 
#Comments are sometimes made this way
 
somethingAgain{ 
#comments that explains what's below them
I:dentifier:something, I, do, not, need
#see ^that
A:notherIdentifier:boolean
//and so on..
}

And I have to make so that the numbers contained in something{} in all the files don't match. I could ask to make so that the input file is only one, and it is formatted this way:

identifier=1234
anotherIdentifier=1235
anotherOne=12345
//and so on...

but I don't know how to do the rest of the program... That's what I've done (the names of the classes, package etc. are in Italian and there's some useless code that NetBeans prevents me from deleting):

package confronto;
import java.awt.Color;
import java.io.*;
import javax.swing.*;
public class confrontoTesti extends javax.swing.JFrame {
 
[Code] ....