Java Reference
In-Depth Information
In this case, two variables step through different ranges. As long as the
loop variable
v
is greater than zero, the exponent value is incremented
and
v
is divided by ten. When the loop completes, the value 10
exp
is the
smallest power of ten that is greater than or equal to
value
. Both the
test value and the exponent are updated on each loop iteration. In such
cases, a comma-separated list of expressions is a good technique to en-
sure that the two values are always in lockstep.
The body of this loop is simply a
continue
statement, which starts the
next iteration of the loop. The body of the loop has nothing to doall the
work of the loop is in the test and iteration clauses of the
for
statement
itself. The
continue
style shown here is one way to show an empty loop
body; another way is to put a simple semicolon on a line by itself or to
use an empty block with braces. Simply putting a semicolon at the end
of the
for
line is dangerousif the semicolon is accidentally deleted or for-
gotten, the statement that follows the
for
can silently become the body
of the
for
.
All the expressions in the
for
construct are optional. If
initialization-
expression
or
update-expression
is left out, its part in the loop is simply
omitted. If
loop-expression
is left out, it is assumed to be
TRue
. Thus, one
idiomatic way to write an infinite loop is as a "for ever" loop:
for (;;)
statement
Presumably, the loop is terminated by some other means, such as a
break
statement (described later) or by throwing an exception.
Conventionally, the
for
loop is used only when looping through a range
of related values. It is bad style to violate this convention by using ini-
tialization or increment expressions that are unrelated to the boolean
loop test.
