CODEWITHSUNDEEP
javapalindrome
Olivia Pulick
Olivia Pulick

Reputation: 21

Input an empty string in my palindrome function

It won't output a false statement. Not sure why it won't output the correct answer.

When testing, make sure your algorithm works in the following cases:

When given a word that is a palindrome, the algorithm returns "true" When given a word that is not a palindrome, the algorithm returns "false" When given a word that is an empty String, the algorithm does not crash.

 public class Palindrome {
     public static void main(String[] args) {
         String input = "";// Set to test value
         char[] phrase = input.toCharArray();
         System.out.println(isPalindrome(phrase));
    }

 public static boolean isPalindrome(char[] input) {
    if (input == null)
        return false;

    int length = input.length;
    int c = 0;


    while(c <= length/2) {
        if(input[c] != input[length - 1 - c])
            return false;
        c++;
        }
    return true;
    }
}

Upvotes: 1

Views: 689

Answers (1)

Jens Dibbern
Jens Dibbern

Reputation: 1454

You can do it the easy way:

  public static void main(String args[]) {
    System.out.println(isPalindrome("redivider"));
    System.out.println(isPalindrome("normal"));
  }

  public static boolean isPalindrome(String check) {
    return new StringBuilder(check).reverse().toString().equalsIgnoreCase(check);
  }

or just add "|| input.length == 0"

  public static boolean isPalindrome(char[] input) {
    if (input == null || input.length == 0) return false;

    int length = input.length;
    int c = 0;

    while (c <= length / 2) {
      if (input[c] != input[length - 1 - c]) return false;
      c++;
    }
    return true;
  }

Upvotes: 5

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