Java: Access Modifiers and Visibility

To control access and maintain object integrity.

Using private fields ensures that the internal state of an object is not directly accessible from outside the class. This allows the object to control how its data is modified and accessed, promoting encapsulation. By providing public methods, you can validate data before it changes the object's state, like ensuring a product price is never negative in an e-commerce application. For example, a Product class might have a private 'price' field with a public 'setPrice' method that checks for valid values.