In the above example code this.x/this.y refers to existing class that is Level class x and y variables where (double x,double y) are double values passed from unique class to assign values to recent class . Let's demonstrate that this key word refers back to the present-day class instance variable. https://free-this-jav16924.blogsvila.com/28946734/new-step-by-step-map-for-jav-this