"this" : to invoke current class constructor
The this() constructor call can be used to invoke the current class constructor. It is used to reuse the constructor. In other words, it is used for constructor chaining.
Example
class A{
A(){System.out.println("hello a");}
A(int x){
this(); // Current class constructor is called.
System.out.println(x);
}
}
class TestThis5{
public static void main(String args[]){
A a=new A(10);
}}