how to use regex as delimiter for stringtokenizer

Question

I want to retrieve the string between |2~ and |

What is the regex sequence to make this work?

Supposedly I have |2~21381030213jafjs231|adfafafasdfas And I am using

StringTokenizer test = new StringTokenizer(string, delim);

I tried StringTokenizer(string, "//|/2/~%s/|") // doesn't work.

but it doesn't work.

Can you also elaborate how regex work (like how regex sequence works)? Or good link to start looking into.

Thank you

Mike Perrenoud · Accepted Answer · 2013-09-17 14:17:43Z

3

If you need the Regex, .*~(.*)\| will do. And here is a Regex 101 to prove it. Now, to explain the Regex, it's pretty simple:

.* tells the engine to match all characters;
~ then tells the engine to stop when it finds a ~;
(.*) then tells the engine to match all characters and group them as a match;
\| then finally tells the engine to match the | which will stop the grouping.

But to learn Regex, have a look at this site, it's one of the best on the web.

answered Sep 17, 2013 at 14:17

Mike Perrenoud

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5 Comments

Mike Perrenoud Over a year ago

@user2698142, I did explain it as best I could. In order. But for you to get a better understanding have a look at the link I provided at the end of the answer. You need to learn Regex, and that's way outside the scope of this question.

Cruncher Over a year ago

~ then tells the engine to stop when it finds a ~; Given that you used a greedy quantifier for your ., it will stop when it finds a ~, but it searches from the back first.

Mike Perrenoud Over a year ago

@Cruncher, you are correct. It could be modified to be .*?~ instead.

JungJoo Over a year ago

i have to say though that the website that teaches regex makes it even more confusing.

Mike Perrenoud Over a year ago

@JungJoo, it's actually one of the best resources on the web, but Regex isn't a simple language. Do some more searching, and if you find a better resource let me know.

shyam · Accepted Answer · 2013-09-17 14:27:55Z

3

StringTokenizer does not support regex. You need to use the Pattern & Matcher classes

String s = "|2~21381030213jafjs231|adfafafasdfas"; Matcher m = Pattern.compile("\\|\\d~([^|]+)\\|").matcher(s); if ( m.find() ) { System.out.println(m.group(1)); }

edited Sep 17, 2013 at 14:27

answered Sep 17, 2013 at 14:20

shyam

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6 Comments

JungJoo Over a year ago

oh really? i thought delimiter and regex were same thing

Mike Perrenoud Over a year ago

@user2698142, even if it doesn't support Regex, a Regex is what you need for this task. Splitting it on a token wouldn't be good enough. Or it would at least require some interesting sub stringing.

JungJoo Over a year ago

you think its easier to pass it into scanner? and use findinline(regex)?

shyam Over a year ago

findInLine will give you the full match not the group contents you have to modify the regex to use non look ahead+behind

JungJoo Over a year ago

really nice answer, can you explain what you did for the pattern? i dont understand ([^}]+). thanks.

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