http://codingbat.com/prob/p154048 Count overlapping pairs in the form AxA where A has a pair!

CountPairs.java

public int countPairs(String str) {
  if(str.length()<3)
    return 0;
  String sub=str.substring(0,3);
  int n= checkSubstringForPair(sub);
  return n+countPairs(str.substring(1,str.length()));
}

public int checkSubstringForPair(String sub){
  if(sub.charAt(0)==sub.charAt(2))
    return 1;
  return 0;
}