intersection

Illegal intersection types for Java.

How?

I3<Class1, Interface1, Interface2> intersection = new I3<>(object);
intersection.get().class1Method();
intersection.get().interface1Method();
intersection.get().interface2Method();

Why?

Made for usage with Mixin. Mixin made it possible to inject arbitrary interfaces to classes at runtime. To access the injected interface methods, you would need to cast it.

Without intersection:

TargetClass target = /* ... */;
InjectedInterface injected = (InjectedInterface) target;
target.original();   // method from original class
injected.injected(); // method from injected interface

With intersection:

I2<TargetClass, InjectedInterface> intersection = new I2<>(target);
intersection.get().original();
intersection.get().injected();

Worth it? Probably not. With Java 10+ you can (ab)use type inference to cast object to multiple type.

var intersection = (TargetClass & InjectedInterface) target;
intersection.original();
intersection.injected();