Android split string with regex not working

Question

I'm trying to split a string at every "." or "?" and I use this regular expression:

(?<=(?!.[0-9])[?.])

In theory the code also prevents splitting if the point is followed by a number so things like 3.000 are not split and it also includes the point in the new string.

For example if I have this text: "Hello. What's your favourite number? It's 3.560." I want to get thi: "Hello.","What's your favourite number?","It's 3.560."

I've made a simple java program on my computer and it works exactly like I want:

String[] x = c.split("(?<=(?!.[0-9])[?.])");
for(String v : x){
    System.out.println(v);
}

However when I use this same regex in my Android app it doesn't split anything...

x = txt.split("(?<=(?!.[0-9])[?.])");
//This, in my android app, returns an array with only one entry which is the whole string without splitting.

PS. Using (?<=[?.]) works so the problem must be in the (?!.[0-9]) part which is meant to exclude points followed by a number.

In the app the user enters the string but I've been trying with the text in this article: reviews.cnet.com/8301-19736_7-57550564-251/… — JoeyCK
– JoeyCK, Commented Nov 18, 2012 at 15:35

Ωmega · Accepted Answer · 2012-11-18 15:44:20Z

4

Use regex pattern

(?:(?<=[.])(?![0-9])|(?<=[?]))

str.split("(?:(?<=[.])(?![0-9])|(?<=[?]))");

answered Nov 18, 2012 at 15:44

Ωmega

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2 Comments

JoeyCK Over a year ago

Wow! Thanks this one does work! Can you tell me why mine didn't work?

Ωmega Over a year ago

@JouiCK - (1) there should not be a period in your negative lookahead; (2) should not apply negative lookahead for ?; (3) should have lookahead out of lookbehind (recommended)

Ian Roberts · Accepted Answer · 2012-11-18 15:30:42Z

2

Remember that outside a square bracket character class, . in a regular expression means any single character. You need \. to match a literal dot, which in turn means you need \\. in the string literal.

answered Nov 18, 2012 at 15:30

Ian Roberts

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3 Comments

JoeyCK Over a year ago

like this? (?<=(?!\\.[0-9])[?\\.])

JoeyCK Over a year ago

it doesn't work either on Android but it does in the java program, on my computer.

Ian Roberts Over a year ago

Yes, strictly speaking you don't need the \\ inside the [?.] but I don't think it does any harm.

Sri Harsha Chilakapati · Accepted Answer · 2012-11-18 15:51:17Z

1

Try this.

public class Tester {

    public static void main(String[] args){
        String regex = "[?.][^\\d]";
        String tester = "Testing 3.015 dsd . sd ? sds";
        String[] arr = tester.split(regex);
        for (String s : arr){
            System.out.println(s);
        }
    }

}

Output:

Testing 3.015 dsd 
sd 
sds

answered Nov 18, 2012 at 15:51

Sri Harsha Chilakapati

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2 Comments

JoeyCK Over a year ago

This one seems to work but it doesn't return the "." at the end like Omega's one. Thank you anyway! :)

Sri Harsha Chilakapati Over a year ago

The one at the end is easily appendable.

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