this is the format method signature:
format(String s, Object... args)
which mean the first argumet is a String
and a random number of Object argument
that are to be formmated in the String.
format("my name is %s",this.name); //print "my name is Jonathan"
the number of var-args (u did SCJP5, didn't you?) is unknown
since the format Strings (the 2 final Strings) have 2 arguments,
you need to send 2 Object (Strings in this case) to put there...