In this tutorial, we will learn about Java objects. In object-oriented programming language, we design a program using objects and classes.


  • A java object is a combination of data/information and procedures working on the available data.
  • An object is an interface of a class.
  • An object is a real-world entity.
  • An object is a run-time entity.
  • The object is an entity, which has state and behavior.

Example: Pen, Pencil, Apple, Laptop, Laptop bag, Chair, Table, Bike, Car, etc.

It can be physical/logical.

Characteristics of Object

An object has three characteristics:


  • State: Represents the data of an object.
  • Behavior: Represents the behavior of an object, such as deposit, withdraw, etc.
  • Identity: It is used internally by the JVM to identify each object uniquely.

new keyword in Java


The new keyword is used to allocate memory at runtime. All objects get memory in Heap memory area.

How to Create a New Object in Java

There are two ways to create objects in java:

1. class_name object_name = new class_name();

2. object_name = new class_name(); //anonymous or nameless objects

Example:

Demo program to create objects in java.


public class ObjectDemo1{
int num1 = 100;
int num2 = 200;
static int num3 = 300;
static int num4 = 400;

//creating main or static method
public static void main (String[] args){
//main or static area

//creating new object
//ObjectDemo1 obj = new ObjectDemo1();
obj = new ObjectDemo1(); //anonymous or nameless object

//calling instance variables
System.out.println (obj.num1);
System.out.println (obj.num2);

//calling static variables
//System.out.println (obj.num3);
//System.out.println (obj.num4); //not recommended
//static variables – direct access
//System.out.println (num3);
//System.out.println (num4); //not recommended

//calling static variables using class name
System.out.println (ObjectDemo1.num3);
System.out.println (ObjectDemo1.num4); //recommended

}
}

Save this file as 'ObjectDemo1.java'
Compile: $javac ObjectDemo1.java
Execute: $java ObjectDemo1

Output:

100
200
300
400