package Chapter8;

import javax.swing.JOptionPane;

public class PalindromeIgnoreNonAlphanumeric {
 /** Main method */
 public static void main(String[] args) {
 // Prompt the user to enter a string
 String s = JOptionPane.showInputDialog("Enter a string:");

 // Declare and initialize output string
 String output = "Ignoring non-alphanumeric characters, \nis "
 + s + " a palindrome? " + isPalindrome(s);

 // Display the result
 JOptionPane.showMessageDialog(null, output);
 }

 /** Return true if a string is a palindrome */
 public static boolean isPalindrome(String s) {
 // Create a new string by eliminating non-alphanumeric chars
 String s1 = filter(s);

 // Create a new string that is the reversal of s1
 String s2 = reverse(s1);

 // Compare if the reversal is the same as the original string
 return s2.equals(s1);
 }

 /** Create a new string by eliminating non-alphanumeric chars */
 public static String filter(String s) {
 // Create a string buffer
 StringBuilder strBuf = new StringBuilder();

 // Examine each char in the string to skip alphanumeric char
 for (int i = 0; i < s.length(); i++) {
 if (Character.isLetterOrDigit(s.charAt(i))) {
 strBuf.append(s.charAt(i));
 }
 }

 // Return a new filtered string
 return strBuf.toString();
 }

 /** Create a new string by reversing a specified string */
 public static String reverse(String s) {
 StringBuilder strBuf = new StringBuilder(s);
 strBuf.reverse(); // Use the reverse method for StringBuilder object
 return strBuf.toString();
 }
}