How to Instance of a Class in Java

1. Using the new Keyword to Create an Instance of a Class in Java
2. Using the instanceof Operator to Check the Given Type of a Class

In Java, Class and Object are the basic concepts of Object-Oriented Programming.

Class is a blueprint from which objects are created. Instances in Java are known as Objects. An object is a real-life entity, whereas a Class is a group of similar objects.

Using the new Keyword to Create an Instance of a Class in Java

An object is created from the class. Dog is a class that is a real-life entity.

Basically, instance and object are the same thing. We create an instance of the Dog class using the new keyword.

A call to the constructor after the new keyword creates an object and initializes the new class. Hence instance of the Dog class.

public class Dog {
  public Dog(String name) {
    System.out.println("Dog,s name is : " + name);
  }

  public static void main(String[] args) {
    Dog dog = new Dog("Scooby");
  }
}

Output:

Dog,s name is : Scooby

Using the instanceof Operator to Check the Given Type of a Class

In Java, instanceof is a comparison operator is used to check whether an instance is of a specified type or not and returns boolean true or false. If we compare instance with a null type using the instaneof operator, it returns false.

Here, we have Dog as a child class which extends the Animal class. The Dog class has a constructor which takes three string type variables name, color, and breed, respectively.

We created an instance of the Dog class using the new keyword.

An object of a subtype is also a type of parent class. If we check if the instance dog is of type Animal, then the instanceof operator returns true as Dog extends Animal class. Hence dog can be referred to as an instance of Dog or Animal class.

If we compare the dog1 instance that is null as a type of Dog class, then instanceof returns false.

class Animal {}
public class Dog extends Animal {
  public Dog(String name, String color, String breed) {
    System.out.println(name + " is a " + color + " colored " + breed + " Dog");
  }

  public static void main(String[] args) {
    Dog dog = new Dog("Scooby", "brown", "Labrador");
    Dog dog1 = null;
    System.out.println(dog instanceof Dog);
    System.out.println(dog instanceof Animal);
    System.out.println(dog1 instanceof Dog);
  }
}

Output:

Scooby is a brown colored Labrador Dog
true
true
false