Java recursion #3

jr3.java

public int countHi(String str) {
  if (str.isEmpty()) return 0;
  if (str.length()==1)return 0;
 return countHi(str.substring(1))+((str.substring(0,2).equals("hi"))?1:0) ;
}

public boolean array220(int[] nums, int index) {
   if (index >= nums.length-1) return false;
   if (nums.length <= 1) return false;
   
   if (nums[index]*10 == nums[index+1])
       return true;
   
   return array220(nums, index+1);    
}

public String endX(String str) {
  if (str.length() < 1) return str;
  return (str.charAt(0) == 'x')
    ? endX(str.substring(1)) + 'x'
    : str.charAt(0) + endX(str.substring(1));
}
 
 
public int countHi2(String str) {
  if (str.length() < 2) return 0;
  if (str.length() >= 3 && str.charAt(0) == 'x' && str.substring(1,3).equals("hi"))
      return countHi2(str.substring(3));
  return (str.substring(0,2).equals("hi")?1:0)+countHi2(str.substring(1));
}