Class methods

Introduction to Object-Oriented Programming in Java

Sani Yusuf

Lead Software Engineering Content Developer

Example of car properties

Cars can have colors.
Each car has a model.
Cars can also perform actions like go on/off.
Cars can also give us data like a list of devices paired with the car's Bluetooth.

Car Colours

Car Model

Turn Car On

Types of methods

Void methods: Methods that do not return data
Non-Void methods: Returns data back

Void methods

Void methods do not return any data
They are marked with the keyword void


 // Car class
 class Car {

     void honkHorn() {
      // Code for horn to sound
       System.out.println("beep beep");
      }
 }

$$ $$


  // Main class 
  public class Main {  
    public static void main(
      String[] args) {

      Car myNewCar = new Car(); 
      myNewCar.honkHorn(); // beep beep
    }
  }

Creating non void methods

Non void methods always have a return type
Non void methods use the return keyword to return data


 // Formula class
 class Formula {


    // Non void method
    int getSquare(int number) {
        // Return an "int" value
      return number * number;
    }

 }


  // Main class
  public class Main {  
    // main method
    public static void main(
      String[] args) {

      Formula myFormula = 
        new Formula(); 
      // Calling "getSquare" method
      System.out.println(
        myFormula.getSquare(5)); // 25
    }
  }

Let's practice!

Introduction to Object-Oriented Programming in Java