Computer Science 2

Given the following classes, which is a better representation of inheritance: the UML Diagram or the circle within a circle? Why?

public class Mammal{
    protected double age; // in years

    public Mammal(){
        System.out.println( "Mammal()" );
    }

    public Mammal( double age ){
        this.age = age;
        System.out.println( "Mammal("+age+")" );
    }

    public double getAge(){
        return age;
    }

    public void setAge( double age ){
        this.age = age;
    }

    public void speak(){
        System.out.println("Mammal is speaking");
    }
}

and

public class Dog extends Mammal{
    protected String breed;

    public Dog(){
        System.out.println( "Dog()" );
    }

    public Dog( double age, String breed){
        this.age = age;
        this.breed = breed;
        System.out.println( "Dog("+age+", "+breed+")" );
    }

    public String getBreed(){
        return breed;
    }

    public void setBreed( String breed ){
        this.breed = breed;
    }

    @Override
    public void speak(){
        System.out.println("Woof, woof");
    }
}