You don’t #include in Java, you import package.Class. Since Java 6 (or was it 5?), you can also import static package.Class.staticMethodOfClass, which would achieve some forms of what you’re trying to do.
Also, as @duffymo noted, import only saves you from systematically prefixing the imported class names with the package name, or the imported static method names with the package and class name. The actual #include semantics doesn’t exist in Java – at all.
That said, having a “funcs.java” file seems to me like you are starting to dip your toes into some anti-patterns… And you should stay away from these.
There’s no #include in Java.
I would not like a design that had a funcs.java that stored all the variables. Objects are state and behavior encapsulated into a single component. You aren’t designing in an object-oriented way if you do that.
Good names matter. A class named Stuff that extends Stuff2 had better just be a poor example.
That’s not good Java. I wouldn’t consider it to be good C++, either.