Java Reference
In-Depth Information
✓
✓
4.21
Will the program work if
n1
and
n2
are replaced by
n1 / 2
and
n2 / 2
in line 17
in Listing 4.9?
Check
Point
The
break
and
continue
keywords provide additional controls in a loop.
Key
Point
Pedagogical Note
Two keywords,
break
and
continue
, can be used in loop statements to provide addi-
tional controls. Using
break
and
continue
can simplify programming in some cases.
Overusing or improperly using them, however, can make programs difficult to read and
debug. (
Note to instructors
: You may skip this section without affecting students' under-
standing of the rest of the topic.)
You have used the keyword
break
in a
switch
statement. You can also use
break
in a loop
to immediately terminate the loop. Listing 4.12 presents a program to demonstrate the effect
of using
break
in a loop.
break
statement
L
ISTING
4.12
TestBreak.java
1
public class
TestBreak {
2
public static void
main(String[] args) {
3
int
sum =
0
;
4
int
number =
0
;
5
6
while
(number <
20
) {
7 number++;
8 sum += number;
9 if (sum >=
100
)
10
break
;
break
11 }
12
13 System.out.println(
"The number is "
+ number);
14 System.out.println(
"The sum is "
+ sum);
15 }
16 }
The number is 14
The sum is 105
The program in Listing 4.12 adds integers from
1
to
20
in this order to
sum
until
sum
is
greater than or equal to
100
. Without the
if
statement (line 9), the program calculates the
sum of the numbers from
1
to
20
. But with the
if
statement, the loop terminates when
sum
becomes greater than or equal to
100
. Without the
if
statement, the output would be:
The number is 20
The sum is 210
You can also use the
continue
keyword in a loop. When it is encountered, it ends the cur-
rent iteration and program control goes to the end of the loop body. In other words,
continue
breaks out of an iteration while the
break
keyword breaks out of a loop. Listing 4.13 presents
a program to demonstrate the effect of using
continue
in a loop.
continue
statement
