What is object in Java

In Java, an object is a software entity that represents a real-world entity and encapsulates data and behavior. An object has a state and a behavior. The state of an object is defined by its attributes, which are also known as instance variables or fields. The behavior of an object is defined by its methods, which are functions that operate on the object's state.

An object is an instance of a class. A class is a blueprint for creating objects and it defines the structure of the object's state and behavior. A class can be thought of as a blueprint for a house. The blueprint defines the general structure of the house, such as the number of rooms, the location of the doors, and the size of the windows. The object is an actual house built from the blueprint, and it has a specific state, such as the color of the walls and the type of furniture inside.

In Java, objects are created using the new operator and a constructor. A constructor is a special type of method that is called when an object is created. It is used to initialize the object's state.

Here's an example of a class in Java:

class Car {
  // instance variables (attributes)
  private String make;
  private String model;
  private int year;

  // constructor
  public Car(String make, String model, int year) {
    this.make = make;
    this.model = model;
    this.year = year;

  // methods (behavior)
  public void start() {
    System.out.println("The car is starting.");

  public void stop() {
    System.out.println("The car is stopping.");

  public void drive() {
    System.out.println("The car is driving.");

To create an object from this class, you would use the new operator and a constructor, like this:

Car myCar = new Car("Toyota", "Camry", 2020);

Once you have created an object, you can access its state and behavior using dot notation. For example:

System.out.println("Make: " + myCar.make); // outputs: "Make: Toyota"
myCar.start(); // outputs: "The car is starting."
myCar.drive(); // outputs: "The car is driving."
myCar.stop(); // outputs: "The car is stopping."

In Java, objects can also interact with each other by sending messages to each other. This is known as object-oriented communication, and it is achieved by calling methods on objects.

In summary, objects are the fundamental building blocks of object-oriented programming in Java. They represent real-world entities, encapsulate data and behavior, and can interact with each other by sending messages to each other.