Question

A bear is an animal and a zoo contains many animals, including bears. Three classes Animal, Bear, and Zoo are declared to represent animal, bear and zoo objects. Which of the following is the most appropriate set of declarations?
a) public class Animal extends Bear
{
...
}
public class Zoo
{
private Animal[] myAnimals;
...
}
b) public class Animal extends Zoo
{
private Bear myBear;
...
}
c) public class Bear extends Animal, Zoo
{
...
}
d) public class Bear extends Animal implements Zoo
{
...
}
e) public class Bear extends Animal
{
...
}
public class Zoo
{
private Animal[] myAnimals;
...
}

Answer 1

Answer:

a) public class Bear  extends Animal{ ... }

public class Zoo {  private Animal[] myAnimals;

... }

Explanation:

The question is an illustration of inheritance in Java programming language.

The syntax to follow is:

class subclass extends superclass {...}

From the question:

Bear $\to$ subclass

Animal $\to$ superclass

So, the following declaration will be used:

class Bear  extends Animal{ ... }

Also from the question, the zoo object represents collection of many animals.

So, its declaration will follow:

class class-name{ ..... }

i.e.

class zoo{ .... }

The ... can then be replaced with declaration of each animal or an array to represent the declarations..

Hence, (e) is correct