Summary

An exception indicates something unexpected happened. A method can handle an exception by catching it or declaring it for the caller to deal with. Many exceptions are thrown by Java libraries. You can throw your own exception with code such as throw new Exception().

Subclasses of java.lang.Error are exceptions that a programmer should not attempt to handle. Subclasses of java.lang.RuntimeException are runtime (unchecked) exceptions. Subclasses of java.lang.Exception, but not java.lang.RuntimeException are checked exceptions. Java requires checked exceptions to be handled or declared.

If a try statement has multiple catch blocks, at most one catch block can run. Java looks for an exception that can be caught by each catch block in the order they appear, and the first match is run. Then execution continues after the try statement. If both catch and finally throw an exception, the one from finally gets thrown.

Common runtime exceptions include:

• ArithmeticException
• ArrayIndexOutOfBoundsException...