public class Bugs {

public static void main(String[] args) {

String email = null;

if (args.length > 0) {

email = args[0];

} else {

System.out.println("Need command line args.");

System.exit(0);

}

// If no command line arguments, what is args.length?

//email = args[0];

// What if email not assigned a value after initialization?

int len = email.length();

// What if email, an aribitrary String, is not a valid email address?

boolean isEmailValid =

(email.endsWith(".com")

|| email.endsWith(".org")

|| email.endsWith(".edu"))

&& containsAtSymbol(email);

}

/**

* A helper method to check for the presense of the @ symbol in a String

*

* @param s a String

* @return true if s contains @, false otherwise

*/

private static boolean containsAtSymbol(String s) {

boolean containsAt = false;

// Can you spot the bugs here before we run the program?

for (int i = 0; i <= s.length(); i++) {

if (s.substring(i, i) == "@") containsAt = true;

// What if @ is early in the string?

}

return containsAt;

}

}