---
title: What is this keyword?
description: "***What is this keyword?*** The*this* keyword in Java is a reference to the current object instance of a class. It is used to differentiate between instance variables and local variables or parameters that have the same name, and to pass…"
url: "https://vinothqaacademy.com/docs/what-is-this-keyword/"
updated: "2025-10-05"
category: Java
tags:
  - Java
---

# What is this keyword?

***What is this keyword?***

The*this* keyword in Java is a reference to the current object instance of a class. It is used to differentiate between instance variables and local variables or parameters that have the same name, and to pass the current object as a parameter to other methods.

### **Key Uses of *this* Keyword:**

**Distinguishing Between Instance Variables and Parameters:** When method or constructor parameters have the same name as instance variables, the *this*keyword helps to differentiate between them.

**Invoking Current Object’s Methods:** The*this* keyword can be used to call other methods of the same class from within a method.

**Passing the Current Object as a Parameter:** The *this* keyword can be used to pass the current object to another method or constructor.

**Returning the Current Object:** The *this* keyword can be used to return the current object from a method.

### **Examples:**

***1. Distinguishing Between Instance Variables and Parameters:***

```javascript

                class Person {

    String name;

    int age;

    // Constructor with parameters

    Person(String name, int age) {

        // 'this.name' refers to the instance variable

        // 'name' refers to the parameter

        this.name = name;

        this.age = age;

    }

    void display() {

        System.out.println("Name: " + this.name);

        System.out.println("Age: " + this.age);

    }

}

public class Main {

    public static void main(String[] args) {

        Person p = new Person("Alice", 30);

        p.display();

    }

}
```

In this example, *this.name* and *this.age* refer to the instance variables, while *name* and *age* are the constructor parameters. The*this* keyword helps to clarify that we are referring to the instance variables.

***2. Invoking Current Object’s Methods:***

```javascript

                class Calculator {

    void add(int a, int b) {

        int result = a + b;

        System.out.println("Sum: " + result);

    }

    void performAddition() {

        // Calling the add method of the same class

        this.add(5, 10);

    }

}

public class Main {

    public static void main(String[] args) {

        Calculator calc = new Calculator();

        calc.performAddition();

    }

}
```

In this example, *this.add(5, 10)* is used to call the *add* method from within another method of the same class.

***3. Passing the Current Object as a Parameter:***

```javascript

                class Printer {

    void printDetails(Person p) {

        System.out.println("Printing details of: " + p.name);

    }

    void print() {

        // Passing the current object as a parameter

        printDetails(this);

    }

}

class Person {

    String name;

    Person(String name) {

        this.name = name;

    }

}

public class Main {

    public static void main(String[] args) {

        Person p = new Person("Bob");

        Printer printer = new Printer();

        printer.print();

    }

}
```

In this example, *this*is used to pass the current *Printer*object to the *printDetails*method.

**4. Returning the Current Object:**

```javascript

                class Chain {

    int value;

    Chain(int value) {

        this.value = value;

    }

    Chain setValue(int value) {

        this.value = value;

        return this; // Returning the current object

    }

    void display() {

        System.out.println("Value: " + this.value);

    }

}

public class Main {

    public static void main(String[] args) {

        Chain obj = new Chain(10);

        obj.setValue(20).display(); // Chaining method calls

    }

}
```

In this example, the *setValue* method returns the current object *(this)*, allowing method chaining.

### **Summary**

The *this* keyword is a powerful feature in Java that helps to refer to the current instance of a class. It resolves naming conflicts, allows method chaining, and provides the ability to pass the current object as a parameter or return it from a method.