HANDLING EXCEPTIONS AND EVENTS - Java Programming: From Problem Analysis to Program Design - page 743

More Examples of Exception Handling
Because Java accepts only strings as input in input dialog boxes and text fields, inputting
data into a string variable won't cause any problems. However, when we use the
methods parseInt , parseFloat ,or parseDouble to convert a numeric string into
its respective numeric form, the program may terminate with a number format error.
This is because the methods parseInt , parseFloat ,and parseDouble each throw a
number format exception if the numeric string does not contain a number. For
example, if the numeric string does not contain an int value, then when the method
parseInt tries to determine the numeric form of the integer string, it throws a
NumberFormatException .

EXAMPLE 11-4

This example shows how to catch and handle number format and division by zero
exceptions in programs that use input dialog boxes and/or text fields.

import javax.swing.JOptionPane;

public class ExceptionExample4
{

public static void main(String[] args) //Line 1

{

int dividend, divisor, quotient; //Line 2

String inpStr; //Line 3

try //Line 4

{

inpStr =
JOptionPane.showInputDialog
("Enter the dividend: "); //Line 5

dividend = Integer.parseInt(inpStr); //Line 6

1
1

inpStr =
JOptionPane.showInputDialog
("Enter the divisor: "); //Line 7

divisor = Integer.parseInt(inpStr); //Line 8

quotient = dividend / divisor; //Line 9

JOptionPane.showMessageDialog( null ,
"Line 10:\nDividend = " + dividend
+ "\nDivisor = " + divisor
+ "\nQuotient =" + quotient,
"Quotient",
JOptionPane.INFORMATION_MESSAGE); //Line 10

}