Java Reference
In-Depth Information
you get back a
Reader
, which you in turn pass to the
BufferedReader
constructor. The usu-
al idiom for writing this in Java is to nest the constructor calls:
BufferedReader is
=
new
new
BufferedReader
(
new
new
InputStreamReader
(
System
.
in
));
You can then read lines of text from the standard input using the
readLine()
method. This
method takes no argument and returns a
String
that is made up for you by
readLine()
con-
taining the characters (converted to Unicode) from the next line of text in the file. If there are
no more lines of text, the constant
null
is returned:
public
public class
class
CatStdin
CatStdin
{
public
public static
static
void
void
main
(
String
[]
av
) {
try
try
{
BufferedReader is
=
new
new
BufferedReader
(
new
new
InputStreamReader
(
System
.
in
));
String inputLine
;
while
while
((
inputLine
=
is
.
readLine
()) !=
null
null
) {
System
.
out
.
println
(
inputLine
);
}
is
.
close
();
}
catch
catch
(
IOException e
) {
System
.
out
.
println
(
"IOException: "
+
e
);
}
}
}
Now that we've covered the
InputStreamReader
, and because it's something that people
have asked me several times, I'll show how to read an
Integer
from the standard input:
public
public class
class
ReadStdinInt
ReadStdinInt
{
public
public static
void
main
(
String
[]
ap
) {
String line
=
null
static
void
null
;
int
int
val
=
0
;
try
try
{
BufferedReader is
=
new
new
BufferedReader
(
new
InputStreamReader
(
System
.
in
));
line
=
is
.
readLine
();
val
=
Integer
.
parseInt
(
line
);
System
.
out
.
println
(
"I read this number: "
+
val
);
new
