Chapter 18
Handling Events
WHAT YOU WILL LEARN IN THIS CHAPTER:
- What an event is
- What an event-driven program is and how it is structured
- How events are handled in Java
- How events are categorized in Java
- How components handle events
- What an event listener is and how you create one
- What an adapter class is and how you can use it to make programming the handling of events easier
- What actions are and how you use them
- How to create a toolbar
In this chapter you learn how a window-based Java application is structured and how to respond to user actions in an application or an applet. This is the fundamental mechanism you use in virtually all of your graphical Java programs. When you understand how user actions are handled in Java, you are equipped to implement the application-specific code that is necessary to make your program do what you want.
INTERACTIVE JAVA PROGRAMS
Before you get into the programming specifics of interactive window-based applications you need to understand a little of how such programs are structured, and how they work. There are fundamental differences between the console programs that you have been producing up to now and an interactive program with a graphical user interface (GUI). With a console program, you start the program and the program code determines the sequences of events. Generally everything is predetermined. You enter data when required, and the program outputs data when it wants. At any given time, the specific program code that executes next ...
