Java Reference
In-Depth Information
}
}
Given that the “for each” loop has been in the language for ages, you might be excused for
expecting to be able to write something like
for (char ch : myString) {…}
. Unfortu-
nately, this does not work. But you can use
myString.toCharArray()
as in the following:
public
public class
class
ForEachChar
ForEachChar
{
public
public static
void
main
(
String
[]
args
) {
String s
=
"Hello world"
;
// for (char ch : s) {...} Does not work, in Java 7
for
static
void
for
(
char
char
ch
:
s
.
toCharArray
()) {
System
.
out
.
println
(
ch
);
}
}
}
A “checksum” is a numeric quantity representing and confirming the contents of a file. If
you transmit the checksum of a file separately from the contents, a recipient can checksum
the file—assuming the algorithm is known—and verify that the file was received intact.
Example 3-4
shows the simplest possible checksum, computed just by adding the numeric
values of each character. Note that on files, it does not include the values of the newline char-
acters; in order to fix this, retrieve
System.getProperty("line.separator");
and add its
character value(s) into the sum at the end of each line. Or give up on line mode and read the
file a character at a time.
Example 3-4. CheckSum.java
/** CheckSum one text file, given an open BufferedReader.
* Checksumm does not include line endings, so will give the
* same value for given text on any platform. Do not use
* on binary files!
*/
public
public static
static
int
int
process
(
BufferedReader is
) {
int
int
sum
=
0
;
try
try
{
String inputLine
;
while
while
((
inputLine
=
is
.
readLine
()) !=
null
null
) {
int
int
i
;
for
for
(
i
=
0
;
i
<
inputLine
.
length
();
i
++) {
sum
+=
inputLine
.
charAt
(
i
);
