Program to test a palindrome

[Kelvin Okornoe]

This is a programming assignment I submitted for grading but I want it to be reviewed so I can learn and perfect  the code.

I have not written any unit test code to test the scope of the code...
I will be glad to have your say on it.

I have included the specification of the program as a comment in the first line.
Thank you...

/*
Program Specifications

write two subroutines and a main routine.

The program should prompt the user to enter a string
The program should test the string entered by the user to determine whether it
is a palindrome...
Ignore spaces, punctuation,and capitalization when looking for palindromes
Convert the string to a lower case with the reverse of the same string
if they are equal then the original string is a palindrome.

write a static subroutine that finds the reverse of the string
it should have one parameter type String and return value of type string.

write a second subroutine that takes a String as a parameter and returns a
string. This subroutine should make a new string that is a copy of the parameter
string, except that all the non-letters have been omitted.
The new string should be returned as the value of the subroutine.

You should write a descriptive comment before each subroutine, saying what it does.

Finally write a main() routine that will read in a string from the user and determine
whether or not it is a palindrome.
It should print the string converted to lower case and stripped of any npn-letter
characters. Then it should print the reverse string. Finally, it should say whether
the string is a palindrome.(Use the two subroutine to process the user's string).
 */
import java.util.Scanner;

public class Palindrome {
    public static void main (String[] args) {
        System.out.println("Enter a string to test for a palindrome");
        Scanner userInput = new Scanner(System.in);
        String input = userInput.nextLine();
        String toLowerCaseInput = input.toLowerCase();

        String output = stripNonAlphabetCharacter(toLowerCaseInput);
        System.out.println("stripped: " + output);
        String reserve = reverseString(output);
        System.out.println("reserved: " + reserve);

        if (reserve.equals(output)) {
            System.out.println("This is a palindrome");
        } else {
            System.out.println("This is not a palindrome");
        }
    }

    //This method reverses the striped string from the user.
    private static String reverseString(String input) {
        int i;
        StringBuilder reverse = new StringBuilder();
        for (i = input.length() - 1; i >=0; i-- )
            reverse.append(input.charAt(i));
        return reverse.toString();
    }

    // This method takes string input from the user and strips off any non-alphabet character from it.
    private static String stripNonAlphabetCharacter(String input) {
            return input.replaceAll("[^a-zA-Z]", "");
    }
}

[Campbell Ritchie]

You should always post the exact code; what you posted won't compile.

You should write a descriptive comment before each subroutine, saying what it does.

Which you haven't done. Look at line 32.
Line 61 is indented incorrectly.
Lines 54‑56 show several formatting errors; I shall leave you to count them.

What does line 52 mean? Why are you saying routines and subroutines, which are not Java® words? Please explain your choice of loop types.

[Adrian Grabowski]

Just wanted to add that StringBuilder has built in method reverse()

[Campbell Ritchie]

You can also use the StringBulder#insert() method at position 0.

[Kelvin Okornoe]

This is the exact code of the program, It should be able to compile

/*
Program Specifications

write two subroutines and a main routine.

The program should prompt the user to enter a string
The program should test the string entered by the user to determine whether it
is a palindrome...
Ignore spaces, punctuation,and capitalization when looking for palindromes
Convert the string to a lower case with the reverse of the same string
if they are equal then the original string is a palindrome.

write a static subroutine that finds the reverse of the string
it should have one parameter type String and return value of type string.

write a second subroutine that takes a String as a parameter and returns a
string. This subroutine should make a new string that is a copy of the parameter
string, except that all the non-letters have been omitted.
The new string should be returned as the value of the subroutine.

You should write a descriptive comment before each subroutine, saying what it does.

Finally write a main() routine that will read in a string from the user and determine
whether or not it is a palindrome.
It should print the string converted to lower case and stripped of any npn-letter
characters. Then it should print the reverse string. Finally, it should say whether
the string is a palindrome.(Use the two subroutine to process the user's string).
 */
import java.util.Scanner;

public class Palindrome {
    public static void main (String[] args) {
        System.out.println("Enter a string to test for a palindrome");
        Scanner userInput = new Scanner(System.in);
        String input = userInput.nextLine();
        String toLowerCaseInput = input.toLowerCase();

        String output = stripNonAlphabetCharacter(toLowerCaseInput);
        System.out.println("stripped: " + output);
        String reserve = reverseString(output);
        System.out.println("reserved: " + reserve);

        if (reserve.equals(output)) {
            System.out.println("This is a palindrome");
        } else {
            System.out.println("This is not a palindrome");
        }
    }

    //This method reverses the striped string from the user.
    private static String reverseString(String input) {
        int i;
        StringBuilder reverse = new StringBuilder();
        for (i = input.length() - 1; i >=0; i-- )
            reverse.append(input.charAt(i));
        return reverse.toString();
    }

    // This method takes string input from the user and strips off any non-alphabet character from it.
    private static String stripNonAlphabetCharacter(String input) {
            return input.replaceAll("[^a-zA-Z]", "");
    }
}

Thanks for the comments, I will go ahead and make the changes and report back...
Thank you

[Campbell Ritchie]

Yes, it does compile; sorry for my mistake. The fact that you managed to make me see a spurious compiler error denotes another error in the code, I am afraid. I can hardly think of a worse variable name in this situation than reserve, which is unnecessary anyway.