Class & Object:
===============
class:
=======
==> a category of one or more than one object by sharing different properties (data (attribute) and functionality (method)).
==> a blueprint of one or more than one object by sharing different properties.
==> collection of attributes(data) and methods (behavior/functionality).

class Student{
	int stuid;
	String stuname;
	String stubatch;
	int marks;
	void display()
	{
		sop(id);
	}
}


Object:
=======
==> Any thing/everything in the real world is called as an "object".
==> Instance of the class.

stu1{
	id = 1;
	name = "Neeraj"
	batch = "73-jsfd
	marks = 88
}

Employee	Student		Customer

e1 = "abc", 50k, SDE
e2 = "xyz", 75k, SSDE
====================================================
Creation of the class:
======================
==> to create the class in java:
	we can use "class" keyword.
Syntax:
	class name_of_the_class{
	}
==> we can create the class above the main class and below to the package name.
==> class is the logical entity, for this definition the JVM never reserve any memory.
=================================================

Creation of Object:
===================
==> to create the object, "new" operator (keyword).
Ex: Scanner obj = new Scanner(System.in); // for scanner object creation
Syntax:
	className reference-name/object-name = new className();

Here:
	className ==> for which class we are creating object
	reference-name ==> Object name
	new ==> keyword, which helps to allocate the memory for the object in JVM Heap.
	className() ==> Constructor
		can use to initialize the object.

==> Object we should create always in main().
==> Suppose, we have created a class and created an object for that class without assignment of data/values then: the object can store in heap memory with default values according to the data type of attributes of the class. 

===========================================
How to assign values for object:
================================

package AshokIT.OOPs;

class Employee{
	int empid;
	String empname;
	double salary;
	
	void display()
	{
		System.out.println("Employee Id = "+empid);
		System.out.println("Employee Name = "+empname);
		System.out.println("EMployee Salary = "+salary);
	}
}

public class MainClass {

	public static void main(String[] args) {
		// creating the object for the given class
		Employee emp1 = new Employee();
		
		System.out.println(emp1.empid); // 0
		System.out.println(emp1.empname); // null
		System.out.println(emp1.salary); // 0.0
		
		emp1.empid = 79697;
		emp1.empname = "Kundana Sri";
		emp1.salary = 67000.00;
		
		System.out.println(emp1.empid); // 0
		System.out.println(emp1.empname); // null
		System.out.println(emp1.salary); // 0.0
		
		emp1.display();
		
		System.out.println("=================================");
		Employee emp2 = new Employee();
		emp2.empid = 79799;
		emp2.empname = "Krishna";
		emp2.salary = 56000.00;
		
		emp2.display();
	}

}

====================================================
Assignment:
===========
Q: WAP TO CREATE THE CLASS "Player" WITH ATTRIBUTES pid, pname, prank, pbatch AND CREATE A METHOD TO DISPLAY THE PLAYER DATA. 

====================================================
Q:1)
====
class Class1{
}
class Class2{
}
public class Class3{
	public static void main(String[] args)
	{
	}
}

what is the file name?
class3.java
==> the IDE can search the class which is with "public" that class name only the name of the java file.
=========================
Q:2) 
class Class1{
}
class Class2{
}
public class Class3{
}
public class Class4{
	public static void main(String[] args)
	{
	}
}

what is the file name?
Ans: Error, because no java file with more than one Public class.