Exception Handling - Java - page 491

Self-Test Exercises (continued)
System.out.println("try block entered:");
number = 42;
if (number > 0)
throw new MyException("Hi Mom!");
System.out.println("Leaving try block.");
}

catch (MyException exceptionObject)
{
System.out.println(exceptionObject.getMessage());
}
System.out.println("End of example.");

The class MyException is on the CD that comes with this text.
15. Suppose that in Self-Test Exercise 14 the catch block were changed to the follow-
ing. (The type MyException is replaced with Exception .) How would this affect the
output?

extra code
on CD

catch (Exception exceptionObject)
{
System.out.println(exceptionObject.getMessage());
}

16. Suppose that in Self-Test Exercise 14 the line

number = 42;

were changed to

number = − 58;

How would this affect the output?
17. Although an exception class normally carries only a string message, you can define
exception classes to carry a message of any type. For example, objects of the following
type can also carry a double “message” (as well as a string message):

public class DoubleException extends Exception
{
private double doubleMessage;

public DoubleException()
{
super ("DoubleException thrown!");
}

public DoubleException(String message)
{
super (message);
}

(continued)