Of this abstraction. The values for getRadius() or getCircumference() in the above example may very well be saved specifically, or they may be calculated, it won't make any difference towards the caller; the setters may or might not have side effects; it doesn't matter towards the caller. Works just like https://propertyingurugram.in/israel-aerospace-industries-subsidiary-leases-45000-sq-ft-office-space-in-gurugram-for-32-lakh-monthly-rent/