Stacks, Parenthesis Checker

[SChaput]

I need to create a program that can read an entire java file and put the whole thing into a string.

File file = new File("test.java");
        StringBuffer contents = new StringBuffer();
        BufferedReader reader = null;
 
        try
        {
            reader = new BufferedReader(new FileReader(file));
            String text = null;
 

            while ((text = reader.readLine()) != null)
            {
                contents.append(text)
                    .append(System.getProperty(
                        "line.separator"));
            }
        } catch (FileNotFoundException e)
        {
            e.printStackTrace();
        } catch (IOException e)
        {
            e.printStackTrace();
        } finally
        {
            try
            {
                if (reader != null)
                {
                    reader.close();
                }
            } catch (IOException e)
            {
                e.printStackTrace();
            }
        }
        

       String contentstoTest = contents.toString();
    }

Thats the easy part. The file test.java is in the string contentstoString. However, after that i need to use stacks to find all the (, { and [, and match them accordingly to their closing ), } and ]. Perfectly, the program will tell me which bracket is unclosed, but for the time being, i would be happy enough just to find a solution that told me if it was balanced or not.
I have found a few variations of a similar program on the internet, but am finding it hard to understand exactly what i need to do to write my own.

public class MatchParen {
  
  
  private boolean matching = true;  


  private java.util.Stack s = new java.util.Stack();   

  public boolean isMatching() {  
    return matching && s.isEmpty();
  }

  public void add(char c) {  
    Character m = leftMatch(c);   // or use leftMatch2
    if (m == null)                // c is not a parenthesis
      ;                              // do nothing (i.e., ignore it)
    else if (m.charValue() == c)  // c is some kind of left parenthesis
      s.push(m);                     // push a Character version, m
    else {                        // c is some kind of right paren
      if (s.isEmpty() || !s.pop().equals(m))  
 matching = false;            // couldn't pop a matching left paren, m
    }
  }



  public void add(String s) {   
    for (int i=0; i < s.length(); i++)
      add(s.charAt(i));   
  }

   

  public static Character leftMatch(char c) {
    switch (c) {
    case '(': 
    case ')':
      return new Character('(');   
    case '[':
    case ']':
      return new Character('[');
    case '{':
    case '}':
      return new Character('{');
    default:
      return null;
    }
  }}

That is the other part of my code, and it does tell me weather or not its balenced. However, like i stated earlier, i would love it if i could change the program to display what line the unmatched symbol is located. Any assistance is greatly appreciated, thanks!

[gloryforixseal]

Now that is what I would call a stack of stacks.

What a fantastic picture.

And the background is what I fell makes it so spectacular.

The stacks on thier own would have been good, with the other kites and goings on, SUPER cool.