The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases.
Here is the complete source code for the VerSig.java program, with some comments added.
Compile and run the program. Remember, you need to specify three arguments on the command line:
Since you will be testing the output of the GenSig program, the file names you should use are
suepksigdataHere's a sample run; the bold indicates what you type.
%java VerSig suepk sig data signature verifies: true