Java Reference
In-Depth Information
EXAMPLE
int
number;
number = keyboard.nextInt();
double
cost;
cost = keyboard.nextDouble();
String word;
word = keyboard.next();
String line;
line = keyboard.nextLine();
PITFALL: Dealing with the Line Terminator,
'\n'
The method
nextLine
of the class
Scanner
reads the
remainder
of a line of text
start-
ing wherever the last keyboard reading left off
. For example, suppose you create an
object of the class
Scanner
as follows:
Scanner keyboard =
new
Scanner(System.in);
and suppose you continue with the following code:
int
n = keyboard.nextInt();
String s1 = keyboard.nextLine();
String s2 = keyboard.nextLine();
Now, assume that the input typed on the keyboard is:
2 heads are
better than
1 head.
This sets the value of the variable
n
to
2
, that of the variable
s1
to
" heads are"
, and
that of the variable
s2
to
"better than"
.
So far there are no problems, but suppose the input were instead
2
heads are better than
1 head.
You might expect the value of
n
to be set to
2
, the value of the variable
s1
to
"heads are better than"
, and that of the variable
s2
to
"1 head."
. But that is not
what happens.
What actually happens is that the value of the variable
n
is set to
2
, that of the vari-
able
s1
is set to the empty string, and that of the variable
s2
to
"heads are better
than"
. The method
nextInt
reads the
2
but does not read the end-of-line character
'\n'
. So the first
nextLine
invocation reads the rest of the line that contains the
2
.
(continued)
