setter : Java Glossary

Setters are just a naming convention. Methods that behave like public variables begin with the lower-case letters set followed by the camel-case name of the internal associated private, possibly virtual, variable, e.g. setWidth(). Setters with a boolean parameter also begin with the letters set e.g. setVisible( true );

Modern IDEs such as IntelliJ Idea will compose a set of getters and setters for you, given just the private instance variables.

Normally within a class you don’t usually use the setters; you go direct to the underlying instance variables, though sometimes it makes sense from a maintenance point of view to channel through setters. Within a package or from outside, you would nearly always go through setters rather than going to directly to public instance variables.

You can also write setters for static classes.