Lecture Notes on 5 Oct 2011

String s = "Humpty Dumpty sat on a wall";

// traverse a string
for (int i = 0; i < s.length(); i++)
{
  char ch = s.charAt(i);
  System.out.println (ch);
}

// this method checks if a string has 6 to 10 characters
// and has at least 1 digit, 1 lower case and 1 upper case letter
public static boolean isValid (String s)
{
  if ((s.length() < 6) || (s.length() > 10))
  {
    return false;
  }
  boolean isDigit = false;
  boolean isLowerCase = false;
  boolean isUpperCase = false;
  for (int i = 0; i < s.length(); i++)
  {
    char ch = s.charAt(i);
    if ((!isDigit) && (ch >= '0') && (ch <= '9'))
    {
      isDigit = true;
    }
    if ((!isLowerCase) && (ch >= 'a') && (ch <= 'z'))
    {
      isLowerCase = true;
    }
    if ((!isUpperCase) && (ch >= 'A') && (ch <= 'Z'))
    {
      isUpperCase = true;
    }
  }

  return (isDigit) && (isLowerCase) && (isUpperCase);
}