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Programming in Java: Object and Classes
The document discusses object orientation, emphasizing the distinction between blueprints (classes) and buildings (objects). It highlights the principles of defining classes, creating objects, and the benefits of object-oriented programming such as code reuse, encapsulation, and control over state and behavior. It concludes that programming in an object-oriented manner enhances the logical structure of code and mirrors real-world representations.
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Programming in Java: Object and Classes
- 1. OBJECTS AND CLASSES MartinChapman martin.chapman@kcl.ac.uk
- 2. •Fundamental principle: •The differencebetween blueprints and buildings
- 3. •Fundamental principle: •The differencebetween blueprints and buildings data type variable variable
- 4. •Fundamental principle: •The differencebetween blueprints and buildings int num1 = 9 num2 = 20
- 5. •Fundamental principle: •The differencebetween blueprints and buildings class object object
- 6. •There are twopredominant ways to understand Object Orientation: •Understand how we do it. •Understand why we do it.
- 7. How do wedo it?
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- 13. 1. Make aclass with methods and variables 2. Make an object (a variable) to link to that class 3. Reference the object to use the methods you made in Step 1.
- 14. 1. Make aclass with methods and variables 2. Make an object (a variable) to link to that class 3. Reference the object to use the methods you made in Step 1.
- 15. Among other reasons... •Itmakes sense •Code reuse •State and behaviour •It gives us control •Constructors •Encapsulation
- 16. Among other reasons... •Itmakes sense •Code reuse •State and behaviour •It gives us control •Constructors •Encapsulation
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- 27. Among other reasons... •Itmakes sense •Code reuse •State and behaviour •It gives us control •Constructors •Encapsulation
- 28. Drive Colour Speed Number ofwheels Number plate Height Stateandbehaviour Paint
- 29. •All the informationwe want our program to have about this object can be categorised as: •“How the object is” (~Nouns / Adjectives). •Colour, numberplate, speed and number of wheels etc. •“What can be done to the object” / “What the object can do” (~Verbs). •Drive and be painted Stateandbehaviour
- 30. •All the informationwe want our program to have about this object can be categorised as: •“How the object is”. •Colour, numberplate, speed and number of wheels etc. •“What can be done to the object” / “What the object can do”. •Drive and be painted STATE BEHAVIOUR Stateandbehaviour
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- 34. Among other reasons... •Itmakes sense •Code reuse •State and behaviour •It gives us control •Constructors •Encapsulation
- 35. CONSTRUCTOR A method whichhas the same name as the class is called an explicit Constructors
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- 39. Among other reasons... •Itmakes sense •Code reuse •State and behaviour •It gives us control •Constructors •Encapsulation
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- 46. • Object orientation,in its simplest form, is code within code. • By programming in an OO manner, we are designing code in a way that both makes sense and gives us control. • OOP makes sense because it allows for efficient reuse and an accurate representation of the world using state and behaviour. • OOP gives us control through constructors and because it enforces encapsulation (a black-box approach to object design in which operations are performed through well-defined method interfaces). SUMMARY