#java #oop #programming #100daysofcode

Java Concepts I’m Mastering –> Part 3: The this Keyword

Continuing my journey of mastering Java fundamentals.

Today’s focus: The this keyword —> small word, big importance.

What is this?

this refers to the current object.

It is mainly used when instance variables and constructor parameters have the same name.

Why Do We Need It?

Without this, Java gets confused between:

Instance variables

Constructor or method parameters

Example

class Student {
    String name;

    Student(String name) {
        this.name = name;  
    }
}

Here:

name (right side) → constructor parameter

this.name → instance variable

Without this, the instance variable wouldn’t be assigned properly.

Other Uses of this

Call another constructor in the same class

Pass current object as a parameter

Return current object

Example (constructor chaining):

class Student {
    String name;
    int age;

    Student(String name) {
        this(name, 18);  
    }

    Student(String name, int age) {
        this.name = name;
        this.age = age;
    }
}

What I Learned

this improves clarity

It avoids ambiguity

It makes constructor design cleaner

Understanding this helped me write more structured OOP code.

Next in the series: Constructor vs Method in Java