Trouble splitting string with split(regex) Java

Question

I want to split a number of strings similar to name: john, id: 20, dest: toledo, from: seattle, date_time: [2/8/12 15:48:01:837 MST] into only these tokens:

john
20
toledo
seattle
[2/8/12 15:48:01:837 MST]

I'm doing this

String delims = "(name|id|dest|from|date_time)?[:,\\s]+";
String line = "name: john, id: 20, dest: toledo, from: seattle, date_time: [2/8/12 15:48:01:837 MST]";
String[] lineTokens = line.split(delims, 5);

for (String t : lineTokens)
{
    // for debugging
    System.out.println (t);
    // other processing I want to do
}

but every even element in lineTokens turns out to be either empty or just whitespace. Each odd element in lineTokens is what I want, i.e. lineTokens[0] is "", lineTokens[1] is "john", lineTokens[2] is "", lineTokens[3] is "20", etc. Can anyone explain what I'm doing wrong?

James Montagne · Accepted Answer · 2012-02-26 02:23:07Z

3

The problem is that your regex is not matching , id: as a whole, it is matching , as one and then id: as a 2nd match. Between these two matches you have an empty string. You need to modify it to match the whole thing. Something like this:

String delims = "(, )?(name|id|dest|from|date_time)?[:\\s]+";

http://ideone.com/Qgs8y

answered Feb 26, 2012 at 2:23

James Montagne

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2 Comments

Nate Over a year ago

This works. I'm curious as to why the 0th index of lineTokens is still empty though, and why you pass 6 in for split()'s second argument (seems like it's just because the 0th index is empty).

James Montagne Over a year ago

Oh, the answer to both of those is the same actually. If your string starts with a delimiter you're going to get an empty string as your first match. Need to ignore that match.

Community · Accepted Answer · 2020-06-20 09:12:55Z

2

Why not a little less complicated regex solution.

String str =  "name: john, id: 20, dest: toledo, from: seattle, date_time: [2/8/12 15:48:01:837 MST]";
String[] expr = str.split(", ");
for(String e : expr)
System.out.println(e.split(": ")[1]);

Output =

john

20

toledo

seattle

[2/8/12 15:48:01:837 MST]

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Feb 26, 2012 at 2:34

RanRag

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2 Comments

Ismail Badawi Over a year ago

Technically ", " and ": " are still regexes.

RanRag Over a year ago

@isbadawi: nice catch but you know what i mean.

user1227804 · Accepted Answer · 2012-02-26 02:51:48Z

1

I made some changes to your code:

    String delims = "(name|id|dest|from|date_time)[:,\\s]+";
    String line = "name: john, id: 20, dest: toledo, from: seattle, date_time: [2/8/12 15:48:01:837 MST]";
    String[] lineTokens = line.split(delims);

    for (String t : lineTokens)
    {
        // for debugging
        System.out.println (t);
        // other processing I want to do
    }

also you should ignore the first element in lineTokens, since it's the capturing from the beginning of the line till "name:...."

answered Feb 26, 2012 at 2:51

user1227804

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1 Comment

Nate Over a year ago

have you tested this? I think the output from your code would be, like, lineTokens[1] == "john, " instead of lineTokens[1] == "john"

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