P1: Game Classes

P1: Game Classes (42 marks)
Focus: basics of classes and objects, polymorphism
In this part, you are required to create classes that represent our game objects. The UML design is given
below followed by a brief description of each class.
[20 marks] (A) Animal class contains:
o [+1] Six private attributes:
• name (String) - the animal’s name.
• energy (double) - the animal’s energy level (must be from 0 to 100).
• alive (boolean) - true only when energy > 0.
• mealAmount (double) - the maximum amount of food the animal can eat when we
call its eat method (must be from 0 to 100).
• x and y (double) - the animal’s location (no restrictions on the values).
• speedX and speedY (double) - the speed in x and y directions (no restrictions on
the values).
o [+1] One zero-arg constructor that sets energy to 100 and both, speedX and speedY to 1
o Several public methods:
• [+2] Setters and getters for all attributes except alive which should have only a getter
method.
• Note the following:
• [+2] your code must respect the restrictions on the values as indicated above.
• [+2] The energy’s setter method should also display a message whenever the
animal is hungry, e.g. “Cow1 is hungry”, or starving, e.g. “Cow1 is
starving”, where Cow1 is the animal’s name. An animal is starving when its
energy ≤ 17 and it is hungry when its energy is between 17 and 50.
• [+2] toString method that returns a string representation of the animal’s status
similar to the following format:
Cow1: alive at (0.0,0.0) Energy=100.0
• [+2] void move(): if the animal is alive, increment x by speedX and y by speedY
, and decrement energy by 0.1. If the animal is dead, display a message to indicate that
it is dead, e.g. “Cow1 can’t move. It is dead!”
FarmTest Farm Animal
Chicken Cow Llama
has-a
(composition)
is-a
(inheritance)
• [+2] void speak(String msg) which displays the given msg on the console only
if the animal is alive, e.g. “Cow1 says: Hi.”
• [+2] void sound(): if the animal is alive, display on the console “Unknown
sound”.
• [+4] double eat() which increments energy according to the following rules:
• An animal can only eat if it is alive and not full. If it is dead, display a message
such as “Cow1 is dead!”. If it is full, display a message such as “Cow1
didn’t eat as it is full!”
• When we call eat(), the animal will eats a maximum of mealAmount. For
example, if Cow1’s mealAmount is 20 and its energy is 60, then the amount
it eats after calling the eat() method will be 20 and its energy will be 80. On
the other hand, if Cow1’s energy is 95, it will eat only 5 units, bringing its
energy to 100.
• The eat() method returns whatever amount of food the animal eats. This will
be deducted from the amount of available food on the farm (will discuss this
shortly).
• The eat() method should print on the console the amount eaten, e.g. Cow1
ate 5 units, now it is full!
[10 marks] (B) Cow, Chicken, and Llama classes: in each class, do the following:
o [+3] Override the sound()method in order to display: “Moo” for Cows, “Hmmm!” for Llamas,
and “Cluck!” for chicken. An animal can make a sound only if it is alive.
o [+3] Add one more method to each class: void swim() to Chicken, Jump() to Llama, and
Milk() to Cow. Each method should display some text about how the animal can perform
these actions (few words should do).
o Add a zero-arg constructor that:
• [+1] Sets mealAmount to: 20 for Cow, 9 for Llama, and 5 for Chicken.
• [+3] Automatically assigns a name to every new object that is composed of the class
name followed by a number that is incremented automatically for every new object.
For example, assume you create 5 animals in this order: 2 cows, a chicken, another
cow, and another chicken. Your code should automatically give the first two cows the
names Cow1 and Cow2, then the name Chicken1 to the first chicken, then name
Cow3 to the third cow, and finally the name Chicken2 to the second chicken.
[10 marks] (C) the Farm class contains:
o [+1] An array animals which when initialized will hold a list of 4 animals: a Chicken, a Cow,
and 2 Llamas.
o [+1] A private double attribute availableFood which represents the amount of food
available in the farm for the animals (must be from 0 to 1000).
o [+2] A zero-arg constructor that sets availableFood to 1000 and initializes animals.
o [+2] A public method void makeNoise() that causes all animals to sound().
o [+2] A public method void feedAnmials() that iterates over each animal, calls its eat()
method, and then decrements availableFood by the amount eaten. Once the
availableFood is not enough to feed the animal, your code should display a message that there
is not enough food in the farm.
o [+2] Setters and getters for all attributes except animals which should have only a getter
method.
[2 marks] (D) FarmTest class is used solely to test other classes and ensure the code works properly. For
example, copy the code below to your program and run it:
public class FarmTest {
public static void main(String[] args) {
Farm myFarm = new Farm();
for(Animal a: myFarm.getAnimals())//move each animal by random amount
for(int i=0; i<(int)(Math.random()*1000); i++) a.move();
System.out.println("Before feeding: " + myFarm.getAvailableFood());
myFarm.feedAnimals();
System.out.println("After feeding: " + myFarm.getAvailableFood());
myFarm.makeNoise();
myFarm.getAnimals()[0].speak("Hello!!");
System.out.println(Arrays.toString(myFarm.getAnimals()));
}
}
Above code should print an output similar to the one below. Note that this output may be slightly
different based on several factors such as your animals’ energy and the available food in the farm.
Before feeding: 1000.0
Chicken1 ate 5.0 units
Cow1 ate 0.3 units. Now it is full!
Llama1 ate 5.5 units. Now it is full!
Llama2 ate 1.8 units. Now it is full!
After feeding: 987.4
Cluck!
Moo!
Hmmm!
Hmmm!
Chicken1 says: Hello!!
[ Chicken1: alive at (50.0,50.0) Energy=95.0 ,
Cow1 : alive at (3.0,3.0) Energy=100.0 ,
Llama1 : alive at (55.0,55.0) Energy=100.0 ,
Llama2 : alive at (18.0,18.0) Energy=100.0 ]
Note: the last four lines will actually be printed on the same line on the console, but I put them here on
four separate lines for clarity. Also, double values may have minor precision error on your machine (e.g.
987.4 may display as 987.400000000001).
Feel free to change the code in FarmTest to test other methods in your classes. You will get the full
mark for this part (i.e. part (D)) if you just try the code given above and it works.
Submission Instructions
For this part of the project, you need to do the following:
1- Create a Java project of with any name of your choice.
2- Create a package with the name P1 and write your code within this package.
3- Zip the package P1 and name the zipped file as: YourStudentID_P1. e.g., “1234567_P1”.
4- Submit the zipped file to Canvas.
Note that you can resubmit an assignment one more time, but the new submission overwrites
the old submission and receives a new timestamp.