inheritance.md

Inheritance is a process of acquiring parent properties and behaviour by a child automatically. Hence you can either reuse or extend parent properties or behaviour in the child class. The main advantage of inheritance is code reusability. Use the keyword extends to inherit from a class.

Type of Inheritance

1. Single Inheritance

When a child inherits properties from a single parent

Below is an example of single inheritance

class Apple {
  protected String brand = "Apple";        
  public void Features() {                    
    System.out.println("Capacity : 256 GB");
    System.out.println("Liquid retina HD Display of 6.1 inches.");
    System.out.println("Dual 12MP Ultra Wide and Wide cameras");
  }
}

class iPhone extends Apple {
  private String model = "iPhone 11";    
 
	public static void main(String[] args) {

    iPhone myMobile = new iPhone();

    System.out.println(myMobile.brand + "'s new realease is " + myMobile.model);
    myMobile.Features();

  }
}

2. Hierarchical inheritance

When multiple children inherit properties from a parent

Below is an example of hierarchical inheritance

class A {
	public void print_A() 
  { 
    System.out.println("Class A"); 
  }
}

class B extends A {
	public void print_B() 
  { 
    System.out.println("Class B");
  }
}

class C extends A {
	public void print_C() 
  {
    System.out.println("Class C");
  }
}

class D extends A {
	public void print_D() 
  {
    System.out.println("Class D");
  }
}

public class Test {
	public static void main(String[] args)
	{
		B obj_B = new B();
		obj_B.print_A();
		obj_B.print_B();

		C obj_C = new C();
		obj_C.print_A();
		obj_C.print_C();

		D obj_D = new D();
		obj_D.print_A();
		obj_D.print_D();
	}
}

3. Multilevel inheritance

When a parent properties are inherited by a child which again get interited by another child. For example, B is inherited from A and C is inherited from B.

A -> B -> C

class A {
	public void printA()
	{
		System.out.println("Class A");
	}
}

class two extends one {
	public void printB() 
  { 
    System.out.println("Class B"); 
  }
}

class three extends two {
	public void printC()
	{
		System.out.println("Class C");
	}
}

// Drived class
public class Main {
	public static void main(String[] args)
	{
		three g = new three();
		g.printA();
		g.printB();
		g.printC();
	}
}

4. Multiple inheritance

When a child inherits its properties from two or more parents. It can be done by the help of Interface.

Below is an example of multiple inheritance.

interface one {
	public void printA();
}

interface two {
	public void printB();
}

interface three extends one, two {
	public void printC();
}
class child implements three {
	public void printA()
	{
		System.out.println("Interface");
	}

	public void printB() 
  { 
    System.out.println("Class B"); 
  }

  public void printC() 
  { 
    System.out.println("Class C"); 
  }
}

public class Main {
	public static void main(String[] args)
	{
		child c = new child();
		c.printA();
		c.printB();
		c.printC();
	}
}

5. Hybrid inheritance

Hybrid inheritance is a combination or two or more inheritance types.

Below is the example of hybrid inheritance.

public class ClassA 
{

}
public class ClassB extends ClassA
{

}
public class ClassC extends ClassA 
{

}
public class ClassD extends ClassB 
{

}

Practice with more examples here