Actually, running the class straight from the command line can be a really cool way of doing ad-hoc unit testing. You can have a main method that instatiates a

Actually, running the class straight from the command line can be a really cool way of doing ad-hoc unit testing. You can have a main method that instatiates an instance of the class, populates it with whatever it needs (including mocks if you're into that sort of thing) and then exercises the various methods of the object. It's like IoC but without all the bread and circuses. NB: it's been about 8-10 years since I did anything like that. Running from the command line is good for something that can run headless but you want to see immediate success/failure type messages. The other main use I had for programs run from the command line was small 'one-off' file format conversion programs. Once you've done half a dozen of these it's relatively easy to just bang out the ~100 lines of code to do this (including proper exception handling). Would it be faster to write it out in perl? Well, if the regex is sufficiently simple then yes, if it is moderately complex then you still use far fewer keystrokes, but getting it to the point that it is correct, that's easier in Java. (Assuming you optimise for readability, something perl... struggles ... with)