In JavaScript this is how we can split a string at every 3-rd character
"foobarspam".match(/.{1,3}/g)
I am trying to figure out how to do this in Java. Any pointers?
views:
500answers:
3
+5
A:
import java.util.ArrayList;
import java.util.List;
public class Test {
public static void main(String[] args) {
for (String part : getParts("foobarspam", 3)) {
System.out.println(part);
}
}
private static List<String> getParts(String string, int partitionSize) {
List<String> parts = new ArrayList<String>();
int len = string.length();
for (int i=0; i<len; i+=partitionSize)
{
parts.add(string.substring(i, Math.min(len, i + partitionSize)));
}
return parts;
}
}
Simon Nickerson
2010-02-19 15:31:44
+1 for choosing the simplest way to solve the problem.
Vijay Dev
2010-02-19 15:50:47
keep in mind that 'substring' will create len/partitionSize copies of the original string. So use 'new String(string.substring(...))' to avoid using extra memory.
tulskiy
2010-02-19 19:45:26
If you keep a collection of substrings that cover the entire original string, the new String method will actually waste (n-1)*sizeof(int). The new Strings' char arrays will take the same memory, but each one will have a separate length field. That said, if any substrings are later discarded, new String could reduce memory. I wouldn't worry either way unless the original string is very big.
ILMTitan
2010-02-19 20:58:54
+6
A:
You could do it like this:
String s = "1234567890";
System.out.println(java.util.Arrays.toString(s.split("(?<=\\G...)")));
which produces:
[123, 456, 789, 0]
The regex (?<=\G...) matches an empty string that has the last match (\G) followed by three characters (...) before it ((?<= ))
Bart Kiers
2010-02-19 15:35:56
:) I'd probably go for Simon's solution as well: my co-workers might not like it if I start adding my regex-trickery to the code base.
Bart Kiers
2010-02-19 15:43:25
I'd hate to think someone voted this answer down simply because they don't like regular expressions.
William Brendel
2010-02-19 15:49:23
I would stick to your's and Kenny's advices and go with a non-regex solution. Thanks for the help!
Vijay Dev
2010-02-19 15:49:32
mad props for supreme regex mojo, but as a reader of this code, I'd hunt you down and egg your house. :)
Kevin Bourrillion
2010-02-19 17:54:45
As long as you call this via a correctly named function (ie splitIntoParts) and don't directly embed that line in your code, it's all good. Otherwise, let the hunting begin :)
GreenieMeanie
2010-02-19 17:55:55
Part of what makes this trick so scary is that it won't work in all languages. For example, JavaScript doesn't support `\G`, and Python won't split on a regex that matches zero characters. But then, if Java had a "get all matches" method like every other language does, you wouldn't have had to invent this trick in the first place, @Bart. ;)
Alan Moore
2010-02-20 00:24:04
+9
A:
Java does not provide very full-featured splitting utilities, so the Guava libraries do:
Iterable<String> pieces = Splitter.fixedLength(3).split(string);
Check out the javadoc for Splitter; it's very powerful.
Kevin Bourrillion
2010-02-19 17:52:54
+1 This is the correct answer (also known as: *know and use the libraries*)
Jonik
2010-02-24 19:57:17
I would take this answer over the regex...just because it's more maintainable (e.g. the fact that less people know about RegEx than ppl being able to read "readable" code.)
ShaChris23
2010-03-02 00:50:56