Multiple inhetitance and protected variable in java()

Question

As we know in Java we can't have multiple inheritance and protected variable in interface, so how can I implement this code?

Bar.java

public class Bar {
    protected int  a = 0;
    public void increaseA() {
        a++;
    }
    public void printA() {
        System.out.println(a);
    }
}

Foo.java

public class Foo extends Bar, FooBar {
    @Override
    public void printClassName() {
        printClassName();
        System.out.println("Foo");
    }
}

FooBar.java

public class FooBar {
    void printClassName(){
        System.out.println("FooBar");
    }
}

Main.java

public class Main {
    public static void main(String[] args) {
        Foo foo = new Foo();
        FooBar fooBar = foo;
        foo.printClassName();
        Bar bar = foo;
        bar.increaseA();
        bar.printA();
    }
}

Answer 1

abstract class Bar {
    protected  int  a = 0;
    public  void increaseA() {
        a++;
    }
    public void printA() {
        System.out.println(a);
    }


}

interface FooBar {
    default void printClassName(){
        System.out.println("FooBar");
    }
}

class Foo extends Bar implements FooBar {
    @Override
    public void printClassName() {
        FooBar.super.printClassName();
        System.out.println("Foo");
    }
}



public class Q4 {
    public static void main(String[] args) {
        Foo foo = new Foo();
        FooBar fooBar = foo;
        foo.printClassName();
        Bar bar = foo;
        bar.increaseA();
        bar.printA();
    }
}

And so the output is

FooBar

Foo

1