Java Reference
In-Depth Information
Please enter an integer numerator:
100
Please enter an integer denominator:
7
Result: 100 / 7 = 14
Please enter an integer numerator:
100
Please enter an integer denominator:
0
Exception: java.lang.ArithmeticException: / by zero
Zero is an invalid denominator. Please try again.
Please enter an integer numerator:
100
Please enter an integer denominator:
7
Result: 100 / 7 = 14
Please enter an integer numerator:
100
Please enter an integer denominator:
hello
Exception: java.util.InputMismatchException
You must enter integers. Please try again.
Please enter an integer numerator:
100
Please enter an integer denominator:
7
Result: 100 / 7 = 14
Fig. 11.3
|
Handling
ArithmeticException
s and
InputMismatchException
s. (Part 2 of 2.)
The first sample execution in Fig. 11.3 does
not
encounter any problems. In the
second execution the user enters a
zero denominator
, and an
ArithmeticException
excep-
tion occurs. In the third execution the user enters the string
"hello"
as the denominator,
and an
InputMismatchException
occurs. For each exception, the user is informed of the
mistake and asked to try again, then is prompted for two new integers. In each sample exe-
cution, the program runs to completion successfully.
Class
InputMismatchException
is imported in line 3. Class
ArithmeticException
does not need to be imported because it's in package
java.lang
. Line 18 creates the
boolean
variable
continueLoop
, which is
true
if the user has
not
yet entered valid input.
Lines 20-48 repeatedly ask users for input until a
valid
input is received.
Enclosing Code in a
try
Block
Lines 22-33 contain a
try
block
, which encloses the code that
might
throw
an exception
and the code that should
not
execute if an exception occurs (i.e., if an exception occurs,
the remaining code in the
try
block will be skipped). A
try
block consists of the keyword
try
followed by a block of code enclosed in curly braces. [
Note:
The term “
try
block”
sometimes refers only to the block of code that follows the
try
keyword (not including the
try
keyword itself). For simplicity, we use the term “
try
block” to refer to the block of
