Let's create objects of Lamp class.When designing libraries, one important aspect is the public API surface. To access members defined within the class, you need to create objects. When class is defined, only the specification for the object is defined no memory or storage is allocated. In the above program, turnOn() and turnOff() member functions are public whereas, isOn property is private. If you do not specify the visibility modifier, it will be public by default. You will learn about protected and internal modifiers later in Kotlin visibility modifiers article. internal - any client inside the module can access them.protected - visible to the class and its subclass.private - visible (can be accessed) from inside the class only.This means, the isOn property can be changed from only inside the Lamp class. For example, the isOn property is private. In the above example, isOn property is initialized to false.Ĭlasses, objects, properties, member function etc. In Kotlin, either the property must be initialized or must be declared abstract ( Visit: Kotlin Abstract Class to learn more). The class has one property isOn (defined in same way as variable), and two member functions turnOn() and turnOff(). To define a class in Kotlin, class keyword is used: Since, many houses can be made from the same description, we can create many objects from a class. Based on these descriptions we build the house. It contains all the details about the floors, doors, windows etc. We can think of class as a sketch (prototype) of a house. This article will focus on the basics to keep things simple.īefore you create objects in Kotlin, you need to define a class. You will learn about detail features of an object-oriented programming like: data encapsulation, inheritance and polymorphism as we go on. It has braking, accelerating, changing gears etc.It has current gear, two wheels, number of gear etc.You can turn on and turn off lamp (behavior).In object-oriented style of programming, you can divide a complex problem into smaller sets by creating objects. This article will focus on object-oriented style of programming in Kotlin. You will learn about these concept in later chapters. Kotlin supports features such as higher-order functions, function types and lambdas which makes it a great choice for working in functional programming style. Kotlin supports both functional and object-oriented programming.

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