Download free ebooks at terney.info 2. Simon Kendal. Object Oriented Programming using Java. “To my wife Janice and daughter Cara, without whom life. Object-Oriented Programming. Java – Sun announces Java. ○ – JDK . Forces the user to use an interface to access data. ○ Makes the code . you will walk through object-oriented programming by example; learning to use a . What metaphor does Java use to specify object relationships? Java uses.
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This book will explain the Object Oriented approach to programming and through the use of small exercises, for which feedback is provided, develop some. New and Updated Features xxv • Optional Case Study: Using the UML to Develop an Object-Oriented Design and Java Implementation of an ATM. The UML™. This PDF edition of the book is available under a Creative Commons “objects first” approach to programming and problem solving that was . than using contrived examples of OO concepts, instructors can use some.
Manipulating these objects to get results is the goal of Object Oriented Programming. It is only an logical component and not the physical entity. Its properties data can be price or speed of these cars. While the methods may be performed with these cars are driving, reverse, braking etc. An Object contains both the data and the function, which operates on the data. For example - chair, bike, marker, pen, table, car, etc.
It offers robust and natural mechanism for organizing and structure of any software. For example, in English, the verb run has a different meaning if you use it with a laptop, a foot race, and business.
Here, we understand the meaning of run based on the other words used along with it. The same also applied to Polymorphism. It is a technique of creating a new data type that is suited for a specific application.
For example, while driving a car, you do not have to be concerned with its internal working. Here you just need to concern about parts like steering wheel, Gears, accelerator, etc. In this OOPS concept, the variables of a class are always hidden from other classes. It can only be accessed using the methods of their current class. For example - in school, a student cannot exist without a class.
It defines the diversity between objects. In this OOP concept, all object have their separate lifecycle, and there is no owner. For example, many students can associate with one teacher while one student can also associate with multiple teachers.
It is also called "death" relationship. Instead, they can only call a list of public functions — called methods.
So, the object manages its own state via methods — and no other class can touch it unless explicitly allowed. If you want to communicate with the object, you should use the methods provided. There are people and there is a cat.
They communicate with each other. It may look like this: You can feed the cat.
It also has a private method meow. What they can do is defined in the public methods sleep , play and feed. Each of them modifies the internal state somehow and may invoke meow. Thus, the binding between the private state and public methods is made. This is encapsulation. Abstraction Abstraction can be thought of as a natural extension of encapsulation. In object-oriented design, programs are often extremely large. And separate objects communicate with each other a lot.
So maintaining a large codebase like this for years — with changes along the way — is difficult. Abstraction is a concept aiming to ease this problem. Applying abstraction means that each object should only expose a high-level mechanism for using it.
This mechanism should hide internal implementation details. It should only reveal operations relevant for the other objects. Think — a coffee machine. It does a lot of stuff and makes quirky noises under the hood.
But all you have to do is put in coffee and press a button.
Preferably, this mechanism should be easy to use and should rarely change over time. Another real-life example of abstraction? Think about how you use your phone: Cell phones are complex.
But using them is simple. You interact with your phone by using only a few buttons. You only need to know a short set of actions. Implementation changes — for example, a software update — rarely affect the abstraction you use.
Inheritance OK, we saw how encapsulation and abstraction can help us develop and maintain a big codebase. But do you know what is another common problem in OOP design? Objects are often very similar. They share common logic.
Ugh… So how do we reuse the common logic and extract the unique logic into a separate class? One way to achieve this is inheritance. It means that you create a child class by deriving from another parent class.
This way, we form a hierarchy. The child class reuses all fields and methods of the parent class common part and can implement its own unique part.
For example: A private teacher is a type of teacher. And any teacher is a type of Person. If our program needs to manage public and private teachers, but also other types of people like students, we can implement this class hierarchy. This way, each class adds only what is necessary for it while reusing common logic with the parent classes. So we already know the power of inheritance and happily use it.
But there comes this problem.