import java.util.Scanner;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;
import java.io.*;
import java.awt.*;
import javax.swing.*;
 
public class Palindrometest
{
 public static void main(String[] args) throws IOException
 {
  JFrame frame = new JFrame();
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
  Scanner stdin = new Scanner(System.in);
  //Scanner stdin = new Scanner(new File("input.txt"));
  String line;
 
  do
  {
   System.out.print("Your expression (or return to end): ");
	line = stdin.nextLine();
	//The next 3 lines removes upper case letters, whitespace and punctuation.
	line = line.toLowerCase();
	line = line.replaceAll(" ", "");
	line = line.replaceAll("\\W","");
	if (is_palindrome(line))
	 //System.out.println("that is a palindrome");
	 JOptionPane.showMessageDialog(frame, "That is a palindrome");
	else
	 JOptionPane.showMessageDialog(frame, "That is NOT a palinfrome"); 
	 //System.out.println("that is NOT a palindrome");
  }
  while (line.length() != 0);
 }
 
 public static boolean is_palindrome(String input)
 {
  Queue<Character> q = new LinkedList<Character>();
  Stack<Character> s = new Stack<Character>();
  Character letter;
  int mismatches = 0;
 
  for (int i = 0; i < input.length(); i++)
  {
   letter = input.charAt(i);
	if (Character.isLetter(letter))
	{
	 q.add(letter);
	 s.push(letter);
	}
  }
  while (!q.isEmpty())
  {
   if (q.remove() != s.pop())
	 mismatches++;
  }
  return (mismatches == 0);
 }
}