Intro

interfacegen is meant to relieve some of the boilerplate crap that happens on Java projects.

Unfortunately, Interfaces Are Nice

When testing Java-based systems, it is often times easier to mock/stub out an interface than a class.

E.g. a constructor of:

public class Foo(ISomeInterface foo) {
}

Is more likely to be testable than:

public class Foo(SomeClass foo) {
}

Because SomeClass will have constructor parameters/etc. that depend on real-world things.

Having an interface with only one implementation, just to satisfy mocking/whatever is very annoying.

So, interfacegen is here to help.

If you provide:

@GenInterface
public class SomeClass implements ISomeClass {
    public void doFoo() {
       // implementation
    }
}

interfacegen will spit out:

public interface ISomeClass {
    void doFoo();
}

Any methods you add/remove change to SomeClass will automatically get updated in ISomeClass.

You are basically driving the definition of the interface from its implementation class.

Backwards? Yes.

But so is the whole one-implementation-per-interface-so-we-can-mock predicament.

This is just a band-aid.