evaluate whether or not a string is a palindrome; for example, 'red rum, sir, is murder'

Palindrome.java

/*
 * Palindrome
 */
package palindrome;

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Palindrome {
   
    public static void main(String[] args) {
        System.out.println("enter a string");   
        Scanner scanner = new Scanner(System.in);
        String phrase = scanner.nextLine();

        String palindrome = isPalindrome(phrase) ? "" : "NOT ";
        System.out.println("Phrase IS " + palindrome + "a palindrome");   
    }
    
    public static boolean isPalindrome(String phrase) {
        phrase = phrase.toLowerCase().replaceAll("[^a-zA-Z0-9]","");
        String revPhrase = new StringBuilder(phrase).reverse().toString();
        return phrase.equals(revPhrase);
    }  
}