Class Stadium maintains a list of non$-$player characters and processes any attacks. Initially, the

list $\_$npcs is empty. Non$-$player characters can be added by using the Add method of class

Stadium.

When you tell an object of class Stadium to Attack, one of two things will happen:

$$ If the list of non$-$player characters is not empty, then

o The message $$Bring it on$!$ is sent to the console.

o The first character in the list is told to GetHit using the specified amount of dam$-$

age.

$$ Else

o The message $$Not very effective...$$ is sent to the console.

When you tell an object of class Stadium to AttackAll, one of two things will happen:

$$ If the list of non$-$player characters is not empty, then

o The message $$Charge$!$ is sent to the console.

o Every character in $\_$npcs is told to GetHit using the specified amount of damage.

$$ Else

o The message $$Why$?$ is sent to the console.

The abstract class Character defines the common features of non$-$player characters. There are

two classes of non$-$player characters: Mortal and Immortal. Class Mortal is a kind of Character. Objects of class Mortal also define a field $\_$health. When

creating new objects of class Mortal, use $15$ as initial value for health. When an object of class

Mortal is told to GetHit, then one of two thing will happen:

$$ If the Mortal$$s health is greater than zero, then

o The message $$Odysseus: Ow$!$ is sent to the console, where $$Odysseus$$ is the

$\_$name of the Mortal.

o The field $\_$health is reduced by the value damage.

$$ Else

o The message $$Odysseus: You already got me$!$ is sent to the console, where

$$Odysseus$$ is the $\_$name of the Mortal.

Class Immortal is a kind of Character. When an object of class Immortal is told to GetHit, then

$$ The message $$Zeus: Ha$,$ Nice try.$$ is sent to the console, where $$Zeus$$ is the $\_$name of

the Immortal.

Your task is to:

$1.$ Implement the program described above. You must write code for all classes, methods,

fields, and constructors.

$2.$ Write a Main method to test your implementation:

a$.$ Create a Stadium object.

b$.$ Tell the Stadium object to Attack with $10$ damage.

c$.$ Tell the Stadium object to AttackAll with $5$ damage.

d$.$ Add three Mortal objects to the Stadium object.

e$.$ Add one Immortal object to the Stadium object.

f$.$ Tell the Stadium object to AttackAll with $8$ damage.

g$.$ Tell the Stadium object to Attack with $10$ damage.

h$.$ Tell the Stadium object to AttackAll with $9$ damage. Explain four fundamental principles of object$-$oriented programming. For each principle,

refer to some task that you have completed for COS$20007$ and elaborate how the princi$-$

ple is used to achieve the objective of the task.