Three.
The command line looks like this:
java copyBytes sourceFile to destinationFile
Here is how the program checks the command line:
There are three blanks which must be filled. Here is a list of possible blank-fillers:
args.length == 3
args.length != 3
args[1].toUpperCase().equals("TO")
!args[1].toUpperCase().equals("TO")
&&
||
Fill the blanks (use copy and paste) so that the error message is written out when the command line is incorrect.