RecursiveMethods.java

public class RecursiveMethods{
   public static void main(String[] args){
      System.out.println( isPalindrome("gohangasalamiimalasagnahog") );
      System.out.println( gcd(6807, 19) );
      System.out.println( countEvens( new int[]{1,2,3,4,5}, 0 ) );
   }

   public static int countEvens(int[] arr, int index){
      if( index == arr.length )
         return 0;
      else if( arr[index] % 2 == 0 )
         return 1 + countEvens(arr, index + 1);
      else
         return countEvens(arr, index + 1);
   }

   public static int gcd(int p, int q) {
      if (q == 0)
         return p;
      else
         return gcd(q, p % q);
   }

   public static boolean isPalindrome( String s ){
      if(s.length() <= 1)
         return true;
      else if(! s.substring(0,1).equals(s.substring(s.length()-1,s.length())))
         return false;
      else
         return isPalindrome(s.substring(1, s.length() - 1));
   }

}