CODEWITHSUNDEEP
javastringbuilder
Rahul Mukherji
Rahul Mukherji

Reputation: 199

Does the .equals() method work with StringBuilders?

I am trying to make a program that tests whether a user entered string is a palindrome or not.

This is my code:

import java.util.Scanner;
public class palindrome{
 public static void main(String[] args){
  Scanner input = new Scanner(System.in);
  StringBuilder sb = new StringBuilder();
  System.out.println("Enter text");
  String inputstr = input.nextLine();
  sb.append(inputstr);
  if((sb).equals(sb.reverse())){
    System.out.println("Palindrome");
    }
    else{
    System.out.println("Not a palindrome");
    }
    }
}

There are no compile time errors, however no matter what I enter, the output is palindrome. Is there some sort of incompatibility between .equals() and StringBuilder? If so, is there any workaround?

Upvotes: 1

Views: 202

Answers (1)

Eran
Eran

Reputation: 393986

StringBuilder doesn't override equals, so you should use String's equals instead.

if(sb.toString().equals(sb.reverse().toString()))

P.S even if it did override equals, your test would always return true, since you are comparing a StringBuilder instance to itself (reverse doesn't return a new StringBuilder instance).

Upvotes: 3

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