Fix deprecation in SampleMain.java

[ghost]

@sfuhrm , this is the updated version of my previous pull request. I had to create a new one because I deleted the repository I used.

I removed CmdLineException and matched the formatting of argument.isEmpty() to the other if statements.

[ghost]

Removing the help message on parsing error was a mistake, thanks for correcting that.

The second change depends on whether the program should run given no arguments. However, programs that use args4j will likely require some arguments to run correctly. I agree with this change as well.

[sfuhrm]

Thanks for fixing the deprecations!