Java Reference
In-Depth Information
EXAMPLE:
(continued)
An even better solution is to declare a
boolean
variable to control the
do-while
loop.
Inside the body of the loop, we can set this variable to
false
when the loop should exit.
This technique has the benefit of making the code logic easier to follow, especially if we
pick a meaningful name for the variable. In the following example, it is easy to see that
the loop repeats if
invalidKey
is
true
:
boolean
invalidKey;
do
{
System.out.println("Enter 'A' for option A " +
"or 'B' for option B.");
s = keyboard.next( );
s = s.toLowerCase( );
c = s.charAt(0);
if
(c == 'a')
invalidKey = false;
else if
(c == 'b')
invalidKey = false;
else
invalidKey = true;
}
while
(invalidKey);
Preventive Coding
The best way to make debugging easier is to make no mistakes in the first place.
Although this is unrealistic for programs of any complexity, there are some techniques
we can use to eliminate or reduce the number of bugs in a program.
Incremental development
is the technique of writing a small amount of code
and testing it before moving on and writing more code. The test may require some
new code, or a “test harness,” that will not be part of your final program but exercises
your code in some way to see if it is working. This technique makes debugging easier
because if the test fails, then the error is likely in the small section of the new code that
was just written.
When an error is made, be sure to learn from your mistake so you do not make it
again in the future. Did the mistake occur because of sloppy programming? Was there
some aspect of the program's design that you did not understand or left off before
writing the code? Was there something you could have done to find the error more
quickly or prevent it from happening at all? Are there other errors in your program
similar to the one you just fixed? A critical review of your coding and debugging
techniques should become a learning experience so you do not repeat your mistakes.
Finally, show your code to other programmers. Another developer might be able
to immediately spot an error in your code and eliminate a lengthy debugging process.
Many software development organizations have a formal process called
code review
that involves the inspection of code by other programmers. Such reviews have the
incremental
development
code review
