What is composition how it is used?

The composition is a design technique in java to implement a has-a relationship . Java Inheritance is used for code reuse purposes and the same we can do by using composition. The composition is achieved by using an instance variable that refers to other objects.29 Eyl 2021

Composition offers better test-ability of a class than Inheritance . If one class consists of another class, you can easily construct a Mock Object representing a composed class for the sake of testing. This privilege is not given by inheritance.

The main reason to use composition is that it allows you to reuse code without modeling an is-a association as you do by using inheritance . That allows stronger encapsulation and makes your code easier to maintain as Joshua Bloch explains in the 3rd edition of his book Effective Java.16 Oca 2018

The main reason to use composition is that it allows you to reuse code without modeling an is-a association as you do by using inheritance . That allows stronger encapsulation and makes your code easier to maintain as Joshua Bloch explains in the 3rd edition of his book Effective Java.16 Oca 2018

Inheritance and composition are two programming techniques developers use to establish relationships between classes and objects. Whereas inheritance derives one class from another, composition defines a class as the sum of its parts .

Inheritance and composition are two programming techniques developers use to establish relationships between classes and objects. Whereas inheritance derives one class from another, composition defines a class as the sum of its parts .

For example, if a class Bulb inherits another class Device, then we can say that Bulb is having is-a relationship with Device , which implies Bulb is a device.