Exception Handling - Absolute Java - page 537

Display 9.3 Same Thing Using Exception Handling (part 3 of 3)

Sample Dialogue 3

Enter number of male dancers:
0
Enter number of female dancers:
5
Lesson is canceled. No men.

Sample Dialogue 4

Enter number of male dancers:
4
Enter number of female dancers:
0
Lesson is canceled. No women.

Exception Classes
There are more exception classes than just the single class Exception . There are more
exception classes in the standard Java libraries and you can define your own. All the
exception classes in the Java libraries have—and the exception classes you define should
have—the following properties:
• There is a constructor that takes a single argument of type String .
• The class has an accessor method getMessage() that can recover the string given as
an argument to the constructor when the exception object was created.

try-throw-catch
When used together, the try , throw , and catch statements are the basic mechanism
for throwing and catching exceptions. The throw statement throws the exception. The
catch block catches the exception. The throw statement is normally included in a try
block. When the exception is thrown, the try block ends and then the code in the catch
block is executed. After the catch block is completed, the code after the catch block(s) is
executed (provided the catch block has not ended the program or performed some other
special action).
If no exception is thrown in the try block, then after the try block is completed, program
execution continues with the code after the catch block(s). (In other words, if no exception
is thrown, the catch block(s) are ignored.)

(continued)