In this lab, you are not asked to solve one fixed problem. Instead You have to choose and solve a problem of your choice. The idea is to pick some real world activity of your interest and code it in java. Here are the details.
In object oriented programming/design everything of interest is abstracted as an object. We have seen two powerful and structured ways to create new/more-complex objects from the given ones. The first is designing a new class which may have object references of other classes. This captures "contained in/comprises of" relationship. This is also called composition. The second way is to extend an object via inheritance. It captures "is a" relationship (example: car "is a" vehicle) between objects.
The relationship among many real world entities can be captured using the two notions mentioned above. Here are several examples of inheritance (the first two you may already have seen in tutorial).
1. Sports
Outdoorsports extends Sports
Indoorsports extends Sports
Watersports extends Outdoorsports
Airsports extends Outdoorsports
Surfacesports extends Outdoorsports
Waterpolo extends Watersports
Tabletennis extends Indoorsports
etc.
2. EnggCollege
IIT extends EnggCollege
IITK extends IIT
IITB extends IIT
REC extends EnggCollege
etc.
3. Two dimensional Geometric figures
rectangle extends figure
square extends rectangle
Ellipse extends figure
circle extends figure
polygon extends figure
convex_polygon extends polygon
etc.
4. KitchenUtensil
CookingUtensils extends KitchenUtensil
ServingUtensils extends KitchenUtensil
PressureCooker extends CookingUtensils
DinnerPlate extends ServingUtensils
etc.
Classification is a very common technique in science also (where we group similar things under one name) trees, fruits, flowers, animals have all been classified in various ways. Of course the works of art, paintings, music, dance, drama have also classifications.
In this lab, you are asked to model a real life entity or phenomenon, of your liking using object orientation mechanism of java. The level of details at which you model the phenomenon is upto you. You may keep in mind the following.
It is preferred that you have inheritance hierarchy more than two levels deep.
Interesting examples usually have both composition and inheritance. For example Painting object may be defined using inheritance, then define Exhibition object as a collection of paintings using composition. Similarly a Dance may be a superclass reference (with subclasses representing specific forms of Dance), and DanceProgramme class may have a sequence of Dance references.
When designing a class, focus on what member variables will capture what you wish to model. How you wish to modify these will give you an idea of what methods you would like to keep. You may have some methods which just represent real life action notionally, like play method in the instrument class or perform method in the dance class or draw method in a figure class.
While defining a subclass, think about which methods should be redefined and what new methods must be added to the subclass. For example, suppose you are doing EnggColleges example, entrance exam info. may be kept in the superclass if it is common to all subclasses (say joint entrance exam etc.)
You are not expected to do a lot of coding, about 80-100 lines of code is ok for this lab. So do not model some complex activity in all its detail, pick a small number of aspects and program them.
Design will be easy for you if you choose to model something of your interest. It may be related to your hobby or academic interest.