Am getting this error, how do I fix it?

Question

I just got handed this java program and am having difficulty running. I have no idea of java and am thining this error could be something simple and members may be able to help me.
Error:
Exception in thread "main" java.lang.StringIndexOutOfBoundsException:String index out of range :6
at java.lang.String.substring (string.java:1441)
at edicleanargs.main(edicleanargs.java.54)
The Java code is:
import java.io.*;
import java.lang.String.*;
public class edicleanargs
public static void main(String args[]) throws IOException
BufferedReader fl= new BufferedReader(new InputStreamReader(System.in));
// System.out.print("\nEnter EDI File Name : ");
// s= fl.readLine();
// try {
BufferedReader br= new BufferedReader(new FileReader(args[0]));
// BufferedReader br= new BufferedReader(new FileReader(s));
// ** ** isacnt \\
String text="";
int i=0, xx, rno=0, llen, cnt=0;
while((text= br.readLine())!=null)
if(text.equals(""))
continue;
rno++;
llen= text.length();
i++;
xx=0;
if(text.length() >2)
if ((text.substring(xx, xx+3)).equals("ISA") && (text.substring(xx+4, xx+6).equals("00")))
cnt++;
System.out.println("\n Rows to be Processed: "+ rno+ " \n\nNo of Expected Records : "+ cnt );
// ** ** isacnt //
String waas="";
BufferedReader wa= new BufferedReader(new InputStreamReader(System.in));
System.out.print("\nHit ONLY ENTER key to Continue....");
waas= wa.readLine();
String fname = "";
// String text = new String();
String text2 = new String();
String sttr1="";
String sttr2="", sttr21="", sttr22="";
String stn= "";
String s="", smisc="-";
int flagst=0;
i=0;
int recordno=0;
llen=0;
int n210=0, n212=0, n214=0, n223=0, n810=0, n856=0, n997=0, nmisc=0;
xx=0;
br= new BufferedReader(new FileReader(args[0]));
while((text= br.readLine())!=null)
if(text.equals(""))
continue;
System.out.println(++recordno);
if(text.equals("THEND"))
break;
llen= text.length();
if(llen < 16)
FileWriter outfile = new FileWriter("WkFile_"+ args[1]+ ".edi", true);
outfile.write(text);
outfile.close();
else
sttr21="";
sttr22="";
for(int si=0; si<= llen-6; si++)
     sttr2=text.substring(si, si+3);
          if(sttr2.equals("ISA") && (text.substring(si+4, si+6)).equals("00"))
          sttr21= text.substring(0, si);
          sttr22= text.substring(si, llen);
          text= sttr21;
          break;
} // for
FileWriter outfile = new FileWriter("WkFile_"+ args[1]+ ".edi", true);
outfile.write("\n"+text);
if(!sttr22.equals(""))
outfile.write("\n"+sttr22);
outfile.close();
} // else
} // while not next.record=null
System.out.println("\n--------------------------- Done --------------------------------");
br.close();
// }catch (FileNotFoundException fnf)
// { System.out.println("\n\nError in FileName Encountered.\nIf FileName entered then File Not Found OR \nNot able to create //file //with above FileNmme. Exiting Program...\n");}
} // public s v main
} // public class
Your kind help would be very much appreciated. Please guide me so that I can fix the program and execute this program.

Answer 1

Thank you nerak99. I figured based on the executable batch file that it takes two inputs and I know what to provide. The first input is the file name and second input is the week number(like 10,11,12 etc)
I was told that this java program takes an edi file and cleans it up and generates an output file thats clean. Hope that helps. But could you point to what may be the problem with the code and how I can fix that. It appears that some variable needs to defined differently and as such am getting the out of bound exception. Can you please help me?