Java practice recording 2020-05-

Java practice recording 2020-05-01

Given a string, return a string made of the chars at indexes 0,1, 4,5, 8,9 ... so "kittens" yields "kien".

altPairs("kitten") → "kien"
altPairs("Chocolate") → "Chole"
altPairs("CodingHorror") → "Congrr"

public String altPairs(String str) {
  String result = "";
  
  // Run i by 4 to hit 0, 4, 8, ...
  for (int i=0; i<str.length(); i += 4) {
    // Append the chars between i and i+2
    int end = i + 2;
    if (end > str.length()) {
      end = str.length();
    }
    result = result + str.substring(i, end);
  }
  
  return result;
}