What is an object in Java?

An object is an entity that has a state, specific behavior, and has been created for a specific purpose. In the real world, an object can be imagined exactly as it is (e.g., chair, bike, table, and car).

An object’s relation with a class

An object is always a product of a class. The state of an object can be represented by data members, while the behavior can be represented by methods. Suppose there is a class named Dog that has several data members and methods. In order to store different types of dogs in a pet store’s database, we would need to create different objects.

The following code creates different Dog objects and stores them:

public class Dog {};
Dog GermanShephered = new Dog();
Dog Bulldog = new Dog();
Dog Labrador = new Dog();

class Dog {
    // data members or state
    String breed;
    int age;
    String size;
    String color;
  
    // methods or behavior
    public String getInfo() {
        return ("Breed is: "+breed+" Size is:"+size+" Age is:"+age+" color is: "+color);
    }
    void eat(){};
    void sleep(){};
    void sit(){};
    void run(){};
    
    public static void main(String[] args) {
        Dog GermanShephered = new Dog();
        GermanShephered.breed="German Shephered"; //Initializing and setting the state
        GermanShephered.size="Small";
        GermanShephered.age=2;
        GermanShephered.color="Brown";
        System.out.println(GermanShephered.getInfo());
        Dog BullDog = new Dog();
        BullDog.breed="Bull dog";
        BullDog.size="Big";
        BullDog.age=4;
        BullDog.color="White";
        System.out.println(BullDog.getInfo());
    }
}

What is an object in Java?

An object’s relation with a class

State and behavior

Code