Java™ How To Program (Early Objects), Tenth Edition

Set and Get Methods vs. public Data

It would seem that providing set and get capabilities is essentially the same as making a class’s instance variables public. This is one of the subtleties that makes Java so desirable for software engineering. A public instance variable can be read or written by any method that has a reference to an object containing that variable. If an instance variable is declared private, a public get method certainly allows other methods to access it, but the get method can control how the client can access it. For example, a get method might control the format of the data it returns, shielding the client code from the actual data representation. A public set method can—and should—carefully scrutinize attempts to modify ...