Design an abstract class named Bird to represent a bird. The class contains an void sing() method to print "This bird sings". Design an interface named Flyable to represent anything can fly and contains an void fly() method. Design a concrete class named Chicken as subclass of Bird and override the sing() method to print "Chicken sings" Design a concrete class named Superman as subclass of Flyable and override the fly() method to print "Superman flies" Design a concrete class named Parrot as subclass of Flyable and Bird and override the methods fly() and sing() to print "Parrot flies" and "Parrot sings" separately.

Here's the implementation of the classes and interface:

// Flyable interface
interface Flyable {
    void fly();
}

// Bird abstract class
abstract class Bird {
    public void sing() {
        System.out.println("This bird sings");
    }
}

// Chicken concrete class
class Chicken extends Bird {
    @Override
    public void sing() {
        System.out.println("Chicken sings");
    }
}

// Superman concrete class
class Superman implements Flyable {
    @Override
    public void fly() {
        System.out.println("Superman flies");
    }
}

// Parrot concrete class
class Parrot extends Bird implements Flyable {
    @Override
    public void fly() {
        System.out.println("Parrot flies");
    }
    @Override
    public void sing() {
        System.out.println("Parrot sings");
    }
}

You can now create objects of these classes and call their methods as follows:

Bird bird = new Chicken();
bird.sing(); // Output: "Chicken sings"

Flyable flyingObject = new Superman();
flyingObject.fly(); // Output: "Superman flies"

Parrot parrot = new Parrot();
parrot.sing(); // Output: "Parrot sings"
parrot.fly(); // Output: "Parrot flies"