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All the animals in the animal class have similar behaviours such as eating, drinking, and sleeping.
                 They also have similar properties, such as colour, size, and number of legs.

                 In the same way, a class in Java contains different types of objects that have similar properties
                 and behaviour. After declaring a class, we can create any number of objects from it.

                     BASIC PRINCIPLES OF OOP

                 There are four principles of Object-Oriented Programming (OOP) which are as follows:

                    Encapsulation              Data Abstraction             Inheritance          Polymorphism
                 Let us learn about these in detail.

                 Encapsulation
                 Encapsulation refers to the bundling of data members and member methods into a single unit,
                 or class. This principle ensures that data can only be accessed through associated methods, thus
                 protecting it from outside interference and misuse. This concept is also known as data hiding.

                 A real-life example is a capsule. In general, a capsule is a small case or container, that protects
                 the medication inside from contamination by outside elements.

                 Data Abstraction
                 Data Abstraction is the principle of representing only the essential features of an object while
                 hiding non-essential details from the user.
                 For instance, when traveling in a car as a passenger, you are concerned only with reaching your
                 destination, not with how the driver operates the car by pressing the clutch, brake, and accelerator.

                 Inheritance

                 The procedure of generating a new class with the help of an already created class, by using
                 its properties and functionality is said to be inheritance. It is one of the important pillars of
                 Object-Oriented Programming. For example, in real world, a child inherits the properties (both
                 materialistic and non-materialistic) of its parents, who, in turn inherited them from their parents.

                 Polymorphism

                 The word  Polymorphism comes from the Greek word  meaning “many forms” ("poly" means
                 many and "morphe" means form). It is the ability of a variable, function, or object to take on
                 multiple forms. For example, the term "car" can refer to a family car, a taxi used by the general
                 public, or a pool car used by people.

                     INTRODUCING BLUEJ

                 Previously,  simple  text  editors  such as Notepad were  used to
                 develop Java programs. With advancements in technology,
                 various  Integrated  Development Environments  (IDE)  are  now
                 available, often free of cost. One such IDE is BlueJ.
                 Other examples of IDEs are Netbeans, and Eclipse. In this chapter,
                                                                                                      BlueJ
                 we will talk about BlueJ.


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