Object in java:
The objects are the physically existing entities in java which are used for specific purpose.
Every object has certain state and behaviour, and will perform specific action.
An object has three characteristics:
An object has three characteristics:
- State: represents data of an object.
- Behaviour: represents the functionality of an object such as deposit, withdraw etc.
- Identity: Object identity is typically implemented via a unique ID. The value of the ID is not visible to the external user. But,it is used internally by the JVM to identify each object uniquely.
Object is an instance of a class. Class is a template or blueprint from which objects are created.
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Class in java
A class is a core component of java because without a class we cannot write a single statement in java.A class is a collection of objects that have the same properties. Class contains the fallowing members
- data member
- method
- constructor
- block
syntax
class <class name>{
//blocks
//constructors
//variables
//methods
}
class <class name>{
//blocks
//constructors
//variables
//methods
}
Example of Object and Class
In this example, we have created a Student class that have two data members id and name. We are creating the object of the Student class by new keyword and printing the objects value.
class Employee{
int eno; // instance variable declaration
String ename; // instance variable declaration
public static void main(String ar[]){ // main method
Employee e=new Enployee(); // creating object to employee class
System.out.println(e.eno); // displaying employee number of employee class
System.out.println(e.ename); // displaying employee name of employee class
}
}
class Employee{
int eno; // instance variable declaration
String ename; // instance variable declaration
public static void main(String ar[]){ // main method
Employee e=new Enployee(); // creating object to employee class
System.out.println(e.eno); // displaying employee number of employee class
System.out.println(e.ename); // displaying employee name of employee class
}
}
Out-put:
0
null
0
null
