I've seen this. Most coders just glue third party stuff together with a bit of business logic. Nobody ever writes anything from bare metal, no complex algorithms, nothing. It just takes too long to test your own stuff. The Java world is so rich in libraries that you can always track down something that does what you need.
And as a certifiable.. I mean certified tester, I'm the person who should be testing shit (and lets face it - Too much of the code out there IS shit)
Let the coders code, Find a person who understands HOW to test and let them test.
Also. If you're going to code using a language like JAVA, Write a freaking JUnit test and pass in Min, Max, Max and a mid range value to your methods/objects. Make 100% certain that it handles the data and errors that inevitably WILL happen. Then you have a quick way to REGRESSION TEST when you do a new release...