Java Reference
In-Depth Information
case 5: {
greeting += "Thursday";
}
case 6: {
greeting += "Friday";
}
case 7: {
greeting += "Saturday";
}
}
greeting += " to you.";
System.out.println(greeting );
Listing 5-4 could use a final
else
statement with no comparison. The final
case
in Listing 5-6 could
be a
default
section. Either one works. When I make a single
case
for every option, I prefer to fill it in,
but that's just a matter of style. As with the final
else
, you can use a
default
section either as a shortcut
for all the cases you didn't define or as a way to trap an unexpected value. Only use
default
as a shortcut
if you're absolutely sure of the values (as we can be when using
GregorianCalendar
).
Looping
Java offers three constructs for looping:
•
for
•
while
•
do-while
for
loops are the most commonly used, but
while
and
do
-
while
loops certainly have their uses.
■
Note
All loops have three operations: initialize a variable, test it to see whether we're done, and update the
variable to be tested again. Everything else is just additional detail or alternate syntax, as we see shortly.
For Loops
As a rule, use a
for
loop when you have some value that you can count. For example, whenever you have
an array or a list or an enumeration, you can use a
for
loop based on the number of items present.
Remember our cardinal direction example from Chapter 3? Let's examine that more closely in
Listing 5-7.
