object - Java - Defining a member that extends class A and implements interface B

Question

I have a variable that must meet two conditions, and I want to set them in the definition

I know that I can define either condition with an individual variable, like in any of these examples

private Class<? extends A> variable; //or
private A variable; //or
private Class<? extends B> variable; //or
private B variable;

But is there a way to have the variable meet both conditions?

I was hoping for something like this

private Class<? extends A implements B> variable;

But I can't find any way to do this without typecasting when I need to call it or storing multiple copies of it

Answer 1

You can declare type parameters that have multiple bounds, such as:

public static <T extends A & B> void test(Class<T> clazz)

But you cannot declare a variable that has multiple bounds:

private Class<? extends A & B> variable;  // doesn't work

You can create an abstract class C that extends A and implements B, so that only one bound is required.

abstract class C extends A implements B {}

Then:

private Class<? extends C> variable;