We'll see how in the next chapter. A collection of classes. The built-in Java classes are organized in packages. The Abstract Window Toolkit, one of the biggest and most commonly-used Java packages. An example from a category.
Every object is an instance of some class.
A value that indicates an object. In a state diagram, a reference appears as an arrow. The process of finding objects that have no references and reclaiming their storage space. A complete description of all the variables and objects and their values, at a given point during the execution of a program. A snapshot of the state of a program, shown graphically.