You are all blessed with a professor with a PhD in fault tolerance. Because of this you will be expected to develop fault tolerant programs. This means bounds checking for input numbers and checking a number of possible error conditions for each command. It also means that your parser should never fail or crash because of a malformed command.
A really useful command interpreter would give useful error messages about commands, such as "wrong number of arguments", or "invalid argument type", or even better "second argument was int, expected string". For our purposes it will be sufficient to print a single error message regardless of the error:
Error: Invalid Command.
Your parser must completely ignore blank lines. For all other lines which are not fully formed and correct commands you must print the above error.
As with other parts of the project, your command parser will be tested separately from the remaining requirements of the project. So if you can't get a fully error checking parser you will not be hurt on the other parts of the project. You may assume that for commands other than error checking all commands will be upper case and there will be no spaces within a command. There will be no blank lines and all commands will be valid.
A working parser cannot make any of those assumptions. Commands should be correctly interpreted regardless of case (ie. CREATE_DOCK and creaTe_DOCK should both be interpreted as the CREATE_DOCK command). Spaces and blank lines should be parsed out and ignored.
My advice would be to spend some time thinking out a plan to write a parser which does not require a lot of copy and paste code. You might make parsing a command + list of arguments a single function, for instance, a la scanf. If something goes wrong, throw an exception! (This is what your TA did, and it is doable in java. No claims that this is the *best* way of doing it). If you find that you really love parsing you might check into programs like lex/jlex which are somewhat covered in the compiler class cmsc430. I wouldn't use them for this project though.