Class: class is a user
defined data type that represents an entity, which is a collection of members
and methods.
The
entire set of data and code of an object can be made the user define data type
with help of a class. Infact objects are variables of type class. Once a class
has been defined, we can create any number of objects belonging to that class.
Syntax: class class_name
{
variable
declarations/data members;
function
declarations/member functions;
}
The
class body contains the declarations of variables and functions, which are
called as class members. The variables declare inside the class are known as data
members and functions are known as member functions.
Creating
Objects
Object:
is a
functionable element that is used to access the members and methods of a class.
Simply, object is an instance of class.
The
declaration of an object is similar to that of a variable of any basic type.
Syntax: classname
obj_name=new classname();
Example: student s=new
student();
where
s is an object of class student.
Accessing class members
Once
an object of a class has been created there must be a provision to access its
members. This is done by using the member access operator (.) called as dot.
Syntax:
Object_name.datamember=value;
Object_name.memberfunction(actual_args);
Example:
s.a=10;
s.display();
Example
program:
class
student //userdefined class
{
int sno=10; //members/fields declaration
void show() //method declaration
{
System.out.println("Hai");
}
}
class
simple
{
public static void main(String
[]args)
{
student s=new student();
//object created
System.out.println("Sno="+s.sno); //accessing members of class
s.show(); //calling method
}
}
Output:C:\>javac
simple.java
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