Classes & Objects

Relax. We'll talk through this in plain words — no textbook voice.

Class is the blueprint for building an object. Object is the actual instance created from a class. If you have a Car blueprint, you can build objects like a red car, a blue car, or an electric car.

java

class Car {
  String color;
  String model;

  void drive() {
    System.out.println(color + " " + model + " is driving.");
  }
}

public class Main {
  public static void main(String[] args) {
    Car myCar = new Car();
    myCar.color = "Red";
    myCar.model = "Mustang";
    myCar.drive();
  }
}

Car class has color, model fields and a drive() method. myCar object gets built, its fields get values, and the method gets called.

You should see

Red Mustang is driving.

Real-World Use

Business data structures like a Product object, Customer object, BlogPost object, or Invoice object are all built using classes.

Easy traps

Calling Car.drive() without ever building an object is a mistake — drive() is an instance method, not static, so it has to be called through an object.