You have learned much about Java. Through the course of this book, you have used variables, methods, classes, objects, inheritance, and polymorphism, but there are some key areas of Java we did not cover, including advanced file I/O, networking, threading, and Swing (a GUI widget toolkit). Java is an industrial-strength language used for everything from programming toasters to providing large, online financial systems. Knowing Java will give you the ability to create games, mobile applications, web applications, and much, much more. To continue your Java education, you should consider reading the following resources: