Hour 18. Handling Errors in a Program

What You’ll Learn in This Hour:

• How to respond to exceptions in your Java programs

• How to create methods that ignore an exception, leaving it for another class to handle

• How to use methods that cause exceptions

• How to create your own exceptions

Errors, the bugs, blunders, and typos that prevent a program from running correctly, are a natural part of the software development process. “Natural” is probably the kindest word that’s ever been used to describe them. In my own programming, when I can’t find the cause of an elusive error, I use words that would make a gangsta rapper blush.

Some errors are flagged by the compiler and prevent you from creating a class. Others are noted by the interpreter in response to a problem that keeps it from running successfully. Java divided errors into two categories:

• Exceptions—Events that signal an unusual circumstance has taken place as a program runs

• Errors—Events that signal the interpreter is having problems that might be unrelated to your program

Errors normally aren’t something a Java program can recover from, so they’re not the focus of this hour. You might have encountered an OutOfMemoryError as you worked on Java programs; nothing can be done to handle that kind of error. The program exits with the error.

Exceptions often can be dealt with in a way that keeps a program running properly.