JarCastingPlatypus 
Platypus is a Java Mixins library. It is being heavily used in Minium.
A quick example:
public interface Car {
String drive();
}
public interface Aircraft {
String fly();
}
public interface Delorean extends Car, Aircraft { }
public class CarImpl implements Car {
@Override public String drive() {
return "It can drive";
}
}
public class AircraftImpl implements Aircraft {
@Override public String fly() {
return "It can fly";
}
}
@Test public void testDelorean() {
MixinClass<Delorean> deloreanMixinClass = MixinClasses.create(Delorean.class);
Delorean delorean = deloreanMixinClass.newInstance(new AbstractMixinInitializer() {
@Override
protected void initialize() {
implement(Car.class).with(new CarImpl());
implement(Aircraft.class).with(new AircraftImpl());
}
});
assertThat(delorean.drive(), equalTo("It can drive"));
assertThat(delorean.fly(), equalTo("It can fly"));
}
Besides, Mixin interface and its default implementation, Mixin.Impl will allow maximum fun with complex mixins, where you can chain different interface calls using the .as(Class<?>) method.
For instance, check the delorean.as(Aircraft.class).fly() in the adaptation of the previous example:
public interface Car extends Mixin {
String drive();
}
public interface Aircraft extends Mixin {
String fly();
}
public class CarImpl extends Mixin implements Car {
@Override public String drive() {
return "It can drive";
}
}
public class AircraftImpl extends Mixin implements Aircraft {
@Override public String fly() {
return "It can fly";
}
}
@Test public void testDeloreanCarWithAircrafCapabilities() {
MixinClass<Car> deloreanMixinClass = MixinClasses.create(Car.class, Aircraft.class);
Car delorean = deloreanMixinClass.newInstance(new AbstractMixinInitializer() {
@Override
protected void initialize() {
implement(Car.class).with(new CarImpl());
implement(Aircraft.class).with(new AircraftImpl());
}
});
assertThat(delorean.drive(), equalTo("It can drive"));
assertThat(delorean.as(Aircraft.class).fly(), equalTo("It can fly"));
}