Exception Handling - Java - page 482

String instance variable that can later be recovered with a call to getMessage . The
method getMessage is an ordinary accessor method of the class Exception . The class
DivisionByZeroException inherits this String instance variable as well as the accessor
method getMessage .
For example, in Display 9.4, we give a sample program that uses this exception
class. The exception is thrown using the no-argument constructor, as follows:
throw new DivisionByZeroException();

Display 9.4 Using a Programmer-Defined Exception Class (part 1 of 3)

1 import java.util.Scanner;

We will present an improved version of
this program later in this chapter.

2 public class DivisionDemoFirstVersion
3{

4 public static void main(String[] args)

5 {

6 try

7 {

8 Scanner keyboard = new Scanner(System.in);

9 System.out.println("Enter numerator:");

10 int numerator = keyboard.nextInt();

11 System.out.println("Enter denominator:");

12 int denominator = keyboard.nextInt();

13 if (denominator == 0)

14 throw new DivisionByZeroException();

15 double quotient = numerator/( double )denominator;

16 System.out.println(numerator + "/"

17 + denominator

18 + " = " + quotient);

19 }

20 catch (DivisionByZeroException e)

21 {

22 System.out.println(e.getMessage());

23 secondChance();

24 }

25 System.out.println("End of program.");

26 }

27 public static void secondChance()

28 {

29 Scanner keyboard = new Scanner(System.in);