this keyword

This keyword in java

The this keyword refers to the current object in a method or constructor. The most common use of the this keyword is to eliminate the confusion between class attributes and parameters with the same name (because a class attribute is shadowed by a method or constructor parameter.

 int a;
 basic(int a){ 
    a=a; //   It will give you error

  }

So to solve this problem we use this keyword:

 int a;
 basic(int a){  
    this.a=a; 

 }

Full program of this keyword..

 package com.ritesh;
 class basic{
    int a;
    basic(int a){  //constructor
        this.a=a; // this can be used to refer current class instance variable.

    }
    public int returner(int a){   //method which return a
        return a;
    }

 }

 public class supe {
    public static void main(String[] args) {
        basic b1=new basic(5);
        System.out.println(b1.a);
    }
 }

Some other example..

class Main {

    int age;
    Main(int age){
        this.age = age;
    }

    public static void main(String[] args) {
        Main obj = new Main(8);
        System.out.println("obj.age = " + obj.age);
    }
}