Palindrome String Check Recursively in Java

Palindrome String checking is one of the primitive exercises for String processing char-by-char.

Palindrome String check can also be implemented recursively in Java. This recursive implementation is not efficient as the iterative one because it calls String.substring() subsequently.

package basics;

public class StringUtils {

 public static boolean isPalindrome( String str )
 {
  int sLength = str.length();
  if ( sLength < 2) {
   return true;
  } else if ( str.charAt(0) != str.charAt( sLength-1 ) ) {
   return false; 
  } else if ( sLength == 2 ) {
   return true;
  } else { 
   return isPalindrome( str.substring( 1, sLength-1 ));
  }
  
 }
 
 public static void main(String[] args) {
  
  String str = "madam";
  boolean result = isPalindrome(str);
  System.out.println(str+" is Palindrome = "+result);
  
  str = "qqaacc";
  result = isPalindrome(str);
  System.out.println(str+" is Palindrome = "+result);
  
  str = "cocoococ";
  result = isPalindrome(str);
  System.out.println(str+" is Palindrome = "+result);
 }
}

Create a StringUtils.java file in your workspace.

When the main method inside the StringUtils class executed it is going to print :

madam is Palindrome = true
qqaacc is Palindrome = false
cocoococ is Palindrome = true