Lec08 - OOP/Java Constructors

Object Oriented Programming using Java in Urdu/Hindi

In this video, following points are explained in detail:

1. What is object declaration, instantiation, and initialization
2. What is constructor, how it is created, when its called.
3. What is benefit of making constructors
4. How to make multiple constructors in same class
5. How to call a constructor from another constructor
6. Why we prefer calling setter methods from constructor to initialize instance variables
7. What is default constructor, when its provider by compiler and when its not provided
8. How constructors can enforce certain data must be initialized at the time of object construction
9. What is no argument constructor, and when we must define it
10. What is method overloading

[abubakarsiddique]

Sir, why we need multiple constructors and multiple methods of the same name in a class?

[HassanAli-rg]

sir kia hum private setter method ko call kar skte hain?

[sairasaeed]

Constructor private ho skta? Benefits?

[SaifAli-stwf]

Sir if there are multiple constructors then how we call specific constructor?

[ihsanmuneer]

//MAIN

public class Main {

public static void main(String[] args) {
Class C=new Class(10);

C.areaPerimeter();
}
}

//CLASS

import java.util.Scanner;
public class Class {

private double radius;
Scanner input=new Scanner(System.in);
//Constructor
public Class(int radius){
setRadius(radius); }

//getter setter
public void setRadius(int radius){
if (radius>0)
this.radius=radius; }

public double getRadius() {
return radius; }
public void areaPerimeter(){
int option;
System.out.println("Press 1.To calculate area\nPress 2.To calculate perimeter\nPress 3.To Exit");
option=input.nextInt();
if (option==1){
System.out.println("Enter the Radius: ");
radius=input.nextDouble();
double area=(3.14*(radius*radius));
System.out.println("Area is: "+area);
}
else if (option==2){
System.out.println("Enter the Radius: ");
radius=input.nextDouble();
double perimeter=(2*3.14*(radius));
System.out.println("Perimeter Is: "+perimeter);

}
else if (option==3){
System.out.println("SYSTEM EXIT!");
System.exit(3);
}
}



}

[abdulrehmankhawar]

Sir how to pass variables of constructor to object through scanner?