[Java] This keyword - to refer current class instance variable

This keyword

1. Usage of java this keyword

1) this keyword can be used to refer current class instance variable

2) this() can be used to invoke current class constructor

3) this keyword can be used to invoke current class method

4) this can be passed as an argument in the method call

5) this can be passed as an argument in the constructor call

6) this keyword can also be used to return the current class instance

2. Without this keyword

public class Test { int id; String name; Test(int id, String name){ id = id; name = name; } void display(){ System.out.println(id + name); } public static void main(String[]args){ Test a = new Test(111,"kyle"); Test b = new Test(222,"tom"); a.display(); b.display(); } }

- We use a this key word to distinguish between local variable and instance variable

- we have a this 

Test(int id, String name){ this.id = id; this.name = name; }  

- If local variables and instance variables are different, there is no need to use this keyword