☞The process by which some properties of a class are shared by another class or classes is known as inheritance.
☞It represents IS-A relationship which is also known as parent-child relationship.
☞Base class is a class that is inherited by another class
☞Derived class is one which inherits from a base class.
Base class is also known as Parent class, or Super class. Base class is also known as Child class, or Target class, or Sub class.
☞Syntax :
class Derived_class extends Base_class{ ....... }
☞Private members of the base class cannot be accessed in the derived class.
import java.util.*; class Base_Class{ private int a=50; } class Derive_Class extends Base_Class{ int b=100; public static void main(String[] args) { Derived_Class obj = new Derived_Class(); System.out.println("Value of a : "+obj.a); System.out.println("Value of b : "+obj.b); } }
Exception in thread "main" java.lang.Error: Unresolved compilation problem: The field Base_Class.a is not visible at Derived_Class.main(Derived_Class.java:9)
☞Public members of the base class can be accessed in the derived class.
import java.util.*; class Base_Class{ public int a=50; } class Derive_Class extends Base_Class{ int b=100; public static void main(String[] args) { Derived_Class obj = new Derived_Class(); System.out.println("Value of a : "+obj.a); System.out.println("Value of b : "+obj.b); } }
Value of a : 50 Value of b : 100
☞Protected members of the base class can be accessed in the derived class.
import java.util.*; class Base_Class{ protected int a=50; } class Derive_Class extends Base_Class{ int b=100; public static void main(String[] args) { Derived_Class obj = new Derived_Class(); System.out.println("Value of a : "+obj.a); System.out.println("Value of b : "+obj.b); } }
Value of a : 50 Value of b : 100
☞There are five types of inheritance in java.
1. Single Inheritance 2. Multi-level Inheritance 3. Hierarchical Inheritance 4. Multiple Inheritance 5. Hybrid Inheritance
☞If a single derived class inherits single base class, then it is known as Single Inheritance.
☞If there is a chain of inheritance, then it is known as Multilevel Inheritance.
☞When two or more derived classes inherits a single base class, it is known as Hierarchical Inheritance.
☞When a derived class inherits more than one base class,it is known as Multiple Inheritance.
☞When more than one type of inheritance systems are used together, it is known as Hybrid Inheritance.