How to use split a string after a certain length?

Question

I want to split a string after a certain length.

Let's say we have a string of "message"

Who Framed Roger Rabbit

Split like this :

"Who Framed" " Roger Rab" "bit"

And I want to split when the "message" variable is more than 10.

my current split code :

private void sendMessage(String message){

// some other code ..

String dtype = "D";
int length = message.length();
String[] result = message.split("(?>10)");
for (int x=0; x < result.length; x++)
        {
            System.out.println(dtype + "-" + length + "-" + result[x]); // this will also display the strd string
        }
// some other code ..
}

Do you want to split on what the 11th char?. What should be the OP if message is `abcdefghijklmnop`? — TheLostMind, Nov 13 '15 at 15:23
Have a look at [N-gram generation from a sentence](http://stackoverflow.com/questions/3656762/n-gram-generation-from-a-sentence) — aioobe, Nov 13 '15 at 15:25

Andy Turner · Accepted Answer · 2018-05-08T17:15:45.347

20

I wouldn't use String.split for this at all:

String message = "Who Framed Roger Rabbit";
for (int i = 0; i < message.length(); i += 10) {
  System.out.println(message.substring(i, Math.min(i + 10, message.length()));
}

Addition 2018/5/8:

If you are simply printing the parts of the string, there is a more efficient option, in that it avoids creating the substrings explicitly:

PrintWriter w = new PrintWriter(System.out);
for (int i = 0; i < message.length(); i += 10) {
  w.write(message, i, Math.min(i + 10, message.length());
  w.write(System.lineSeparator());
}   
w.flush();

edited May 08 '18 at 17:15

answered Nov 13 '15 at 15:24

Andy Turner

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This should actually be the right way to go. Its both correct and efficient :) – TheLostMind Nov 13 '15 at 15:43
This works well ! Can u explain how the "message.substring" part works ? – newborn Nov 13 '15 at 16:26
I don't really know what to say. It gets the substring between the i-th character and the (i+10)-th character of the string, or the end of the string if that comes first. – Andy Turner Nov 13 '15 at 16:29
Isn't calculating length on each iteration is a bad idea? I don't know if compiler has optimized code somehow. – vivek Jan 08 '16 at 16:08
@AndyTurner is there any way I can contact you? – vivek Jan 08 '16 at 16:14

score 4 · Answer 2 · answered Nov 13 '15 at 15:43

4

I think Andy's solution would be the best in this case, but if you wanted to use a regex and split you could do

"Who Framed Roger Rabbit ".split("(?<=\\G.{10})");

answered Nov 13 '15 at 15:43

PeterK

1,697
10
20

score 1 · Answer 3 · answered Nov 13 '15 at 15:36

1

You could use a regex find, rather than a split something like this: [\w ]{0,10}

Pattern p = Pattern.compile("[\\w ]{0,10}");
Matcher m = p.matcher("who framed roger rabbit");
while (m.find()) {
    System.out.println(m.group());
}

answered Nov 13 '15 at 15:36

James Harrison

165
6

Why not `".{,10}"`? or `"[\s\S]{,10}"`? – Andy Turner Nov 13 '15 at 15:36
I assumed it was looking for text, but `.` would work better if it was any char. – James Harrison Nov 13 '15 at 15:38
See my comments on Vinod's answer about why it doesn't necessarily match any character. – Andy Turner Nov 13 '15 at 15:43

score 0 · Answer 4 · answered Nov 13 '15 at 15:35

0

This will work for you. Works for any length of message.

public static void main(String[] args) {
    String message =  "Who Framed Roger Rab bit";
    if (message.length() > 10) {
        Pattern p = Pattern.compile(".{10}|.{1,}$");
        Matcher m = p.matcher(message);
        while (m.find()) {
            System.out.println(m.group());
        }   
    }
}

O/ P :

Who Framed
 Roger Rab
 bit

answered Nov 13 '15 at 15:35

TheLostMind

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It'd skip characters [not matched by `.`](http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html#lt), though. – Andy Turner Nov 13 '15 at 15:37
`.` means *anything* :) – TheLostMind Nov 13 '15 at 15:38
It means "Any character (may or may not match line terminators)", according to the javadoc. – Andy Turner Nov 13 '15 at 15:38
@AndyTurner - Ah yes. A multiline pattern would do in that case – TheLostMind Nov 13 '15 at 15:40

How to use split a string after a certain length?

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