1	import java.util.Stack;
     2	import javax.swing.JOptionPane;
     3	
     4	/** Check for balanced parentheses. */
     5	
     6	public class AdvancedParenChecker
     7	{
     8	    // Constants for target characters
     9	    private static final String kOpen = "([{";
    10	    private static final String kClose = ")]}";
    11	
    12	    /** Test the input string to see that it contains balanced parentheses. 
    13	        @param expression A String containing the expression to be examined
    14	        @return true if all the parentheses match
    15	     */
    16	    public static boolean isBalanced(String expression)
    17	    {
    18	        Stack<Character> stack = new Stack<Character>(); // Create an empty stack.
    19	        boolean balanced;
    20	        try
    21	        {
    22	            // Consider all the characters in the expression
    23	            int index = 0;
    24	            while (index < expression.length() && balanced)
    25	            {
    26	                char nextCh = expression.charAt(index);
    27	                // Push any open paren
    28	                if (kOpen.indexOf(nextCh) > 0)
    29	                {
    30	                    stack.push(nextCh);
    31	                }
    32	                // Pop any close paren
    33	                else if (kClose.indexOf(nextCh) > 0)
    34	                {
    35	                    char topCh = stack.pop();
    36	                    balanced = kOpen.indexOf(topCh)
    37	                               == kClose.indexOf(nextCh);
    38	                }
    39	                index++;
    40	            }
    41	        }
    42	        catch (EmptyStackException ex)
    43	        {
    44	            // We know it's unbalanced
    45	            balanced = false
    46	        }
    47	        // Did all parens match? 
    48	        return (balanced && stack.empty());
    49	    }