Hello Jetto Net followers!

Welcome to the fourth part of our Java Object Oriented Programming (OOP) series. In the previous article, I explained the constructors that allow us to create objects. In this article, I will explain the “this” keyword that allows us to understand how objects navigate and refer to themselves.

What is this?

this keyword is a reference used in Java for an object to refer to itself. Each object can use the this keyword to access properties (attributes) and behaviors (methods) within itself. this stands for “this object” and represents whatever object we are currently processing.

Usage Areas of this Keyword

1. Accessing Attributes (Variables): Within an object, if there is an attribute (e.g., brand) and a method parameter (e.g., brand) with the same name, we can access the attribute using the this keyword. You can understand this better in the following code:

public class Car {
    String brand;
    public Car(String brand) {
        this.brand = brand; // this.brand points to the brand within the class.
    }
}

1. Calling Methods: Within an object, we can use the this keyword to call another method.

public class Car {
   
    public void printDetails() {
        System.out.println("Brand: " + this.brand);
    }
}

1. Calling Constructors: Inside a constructor, we can use the this() structure to call another constructor of the same class.

   
   

public class Car {
    // ...
    public Car() {
        this("Ford", "Focus", 2015, "Gray"); // Calling another constructor
    }
    public Car(String brand, String model, int year, String color) {
        this.brand = brand;
        this.model = model;
        this.year = year;
        this.color = color;
    }
}

Importance of the this Keyword

• Code Readability: The this keyword makes the code more readable. It clearly indicates which value belongs to the object's attribute, especially when the attribute and parameter names are the same.
• Code Reusability: The this keyword makes the code more reusable. It is particularly useful in sharing code between constructors using the this() structure.

When Should the this Keyword Not Be Used?

• Inside Static Methods: The this keyword cannot be used inside static methods, as static methods belong to the class, not to an object.
• Accessing Local Variables: The this keyword is not used to access local variables. Local variables are already defined within the method, so they can be accessed directly by their names.

We hope this article helped you understand the this keyword in Java. Feel free to write your questions or thoughts in the comment section.

Happy coding!