Java Recursive method doesn't seem to be returning an exact string

Question

I am trying to make a Palindrome checker in Java but my when I check the reverse method compared to the input string to see if they are equivalent, I am getting false. Even when I use obvious palindromes like "racecar". My reverse method uses recursion to reverse an input string.

public class Palindrome
{
    public static String reverse( String input )
    {
        if( input.length() == 1 )
            return input;
        return reverse( input.substring( 1 ) ) + input.charAt( 0 ); 
    }

    public static boolean isPalindrome( String input )
    {
        if( Palindrome.reverse( input ) == input )
            return true;
        return false;
    }

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

Use .equals method – AndroidRuntimeException Jan 09 '17 at 01:45 — AndroidRuntimeException, Jan 09 '17 at 01:45

score 0 · Answer 1 · answered Jan 09 '17 at 01:52

0

Use .equals() instead of == to fix your code.

Note you could condense your code into something like this:

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

answered Jan 09 '17 at 01:52

Sash Sinha

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Java Recursive method doesn't seem to be returning an exact string

1 Answers1