When Can I use ClassName.this

ClassName.this is used to refer the outer class object from inner class.

Let me explain with an example.

As you see above image, I defined Employee class, where Formatter is the inner class inside it. Formatter class defines formattedInfo method, it accesses the super class object data using ‘Employee.this’.

Find the below working application.

Employee.java

package com.sample.app.model;

public class Employee {
 private int id;
 private String firstName;
 private String lastName;

 public Employee(int id, String firstName, String lastName) {
  this.id = id;
  this.firstName = firstName;
  this.lastName = lastName;
 }

 public int getId() {
  return id;
 }

 public void setId(int id) {
  this.id = id;
 }

 public String getFirstName() {
  return firstName;
 }

 public void setFirstName(String firstName) {
  this.firstName = firstName;
 }

 public String getLastName() {
  return lastName;
 }

 public void setLastName(String lastName) {
  this.lastName = lastName;
 }

 @Override
 public String toString() {
  return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + "]";
 }

 public Formatter formatter() {
  return new Formatter();
 }

 public class Formatter {
  public String formattedInfo() {
   String firstName = Employee.this.firstName;
   String lastName = Employee.this.lastName;
   return firstName.toUpperCase() + "," + lastName.toUpperCase();

  }
 }

}

Test.java

package com.sample.app;

import com.sample.app.model.Employee;
import com.sample.app.model.Employee.Formatter;

public class Test {

 public static void main(String args[]) {
  Employee emp = new Employee(1, "Gopi", "Battu");

  Formatter formatter = emp.formatter();
  String formattedInfo = formatter.formattedInfo();

  System.out.println("Formatted Information : " + formattedInfo);

 }
}

When you ran Test.java, you can able to see below message in console.

Formatted Information : GOPI,BATTU

You may like

Interview Questions

Programming Questions

Miscellaneous

Is array a primitive type or object in java?

How to check an exception is checked or not?

How to check given object is an array or not?

How to get the system hash code of an object?

Can a functional interface have more than one method?

Arrays.asList() throws UnsupportedOperationException while removing element using iterator