To see if a file has balanced curly braces, square brackets

Question

I am writing this class (along with other files that are in a package) to insert characters in a linkedlist and to see if the curly braces, square brackets and parentheses are balanced. For example something like this( I need to have line numbers also );
1. This file is balanced with curly braces, square brackets
2. and parentheses: {}, [] and (). These
3. characters are not required to balance inside
4. quoted strings. E.g., "){[[]".
Input is balanced.
I am not doing it right and that is where I need help or a way to lead me to a solution. I am going crazy, I am losing it....any good idea will help.import java.io.*;
import java.util.StringTokenizer;
class balance
  public static void main(String arg[])
     Queue word = new Queue();
      int index = 0;
     LinkedList itr = new LinkedList();
     LinkedList size = new LinkedList();
        try
            FileReader fr = new FileReader (arg[0]);
            BufferedReader inFile = new BufferedReader(fr);
            String line = inFile.readLine();
             while(line != null)
                line = inFile.readLine();
                   while(size >= line.length() && line.charAt(index) != ' ')
                     Sentence.insert (new Character(line.charAt(index)));
                     index++;
                   while(!Sentence.empty( ))
                            while( itr != null )&& itr.equals( "{" ) || itr.equals( "}"))
                   System.out.print (((Character)Sentence.remove()).charValue());
                   System.out.print ("  ");
                    index++;
            inFile.close();
       catch ( Exception e )
        {  System.out.println( e );  }
      System.exit(0);
}

Answer 1

A fairly easy way is to have one counter variable per bracket-set you want to test for balance and count this vairable up each time you meet an opening bracket (outside a qouted string) and down each time you meet a closing bracket (also outside a qouted string)...
If these counters does not finish with having their initial values (eg. zero) the one set not balanced is the one whose counter variable is not zero (positive for too many opening brackets, negative for too many closing brackets)
eg.
int countSquareBrackets = 0;
int countCurlyBrackets = 0;
int countParenthesis = 0;
if (/*not in string*/)
switch (line.charAt(index)) {
case '[': ++countSquareBrackets; break;
case ']': --countSquareBrackets; break;
case '{': ++countCurlyBrackets; break;
case '}': --countCurlyBrackets; break;
case '(': ++countParenthesis; break;
case ')': --countParenthesis; break;
Hope it leads you closer to a solution,
chrh