We have discussed the theory about access modifiers in the previous note. This note will give you an example code that will show the valid and invalid usages for members belonging to different access levels from different regions of your code such as same class, subclass in same package, subclass in another package and a non-subclass in another package.
Object-Oriented Programming (OOP) uses "objects" to model realworld objects. Object-Oriented Programming (OOP) consist of some important concepts namely Encapsulation, Polymorphism, Inheritance and Abstraction. These features are generally referred to as the OOPS concepts.
There is a class in Java called Object and is present in the package java.lang.Object. This is different from the concept of objects in object oriented programing, and begenners may get confused. Note that is is just a class in Java with the name as Object.
Object class API basics
Class java.lang.Object is the root of the class hierarchy in Java.
Every class has Object as a superclass either directly or indirectly.
Inheritance describes the parent child relationship between two classes.
A class can get some of its characteristics from a parent class and then add more unique features of its own. For example, consider a Vehicle parent class and a child class Car. Vehicle class will have properties and functionalities common for all vehicles. Car will inherit those common properties from the Vehicle class and then add properties which are specific to a car.
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