Extract numbers and names from string

Question

My goal is to extract names and numbers from a string in java. Examples: input -> output

1234 -> numbers: [1234], names: []

1234,34,234 -> numbers: [1234, 34, 234], names: []

12,foo,123 -> numbers: [12, 123], names: [foo]

foo3,1234,4bar,12,12foo34 -> numbers: [1234, 12], names: [foo3, 4bar, 12foo34]

foo,bar -> -> numbers: [], names: [foo, bar]

I came up with [^,]+(,?!,+)* which match all parts of the string, but i dont know how to match only numbers or names (names can contain number - as in example). Thanks

You could just use OR and groups: `(\d+)|([a-zA-Z]+)` [demo](http://regex101.com/r/yB0iS6) — HamZa, Jun 21 '13 at 09:35
Also named groups may be interesting, since I'm not a java dev, take a look at this [answer](http://stackoverflow.com/a/415635/) — HamZa, Jun 21 '13 at 09:36

Lukas Eder · Accepted Answer · 2013-06-21T09:51:43.720

6

Here's a regex-only solution:

(?:(\d+)|([^,]+))(?=,|$)

The first group (\d+) captures numbers, the second group ([^,]+) captures the rest. A group must be followed by a comma or the end of line (?=,|$).

A quick demo:

Pattern p = Pattern.compile("(?:(\\d+)|([^,]+))(?=,|$)");
Matcher m = p.matcher("foo3,1234,4bar,12,12foo34");

while (m.find()) {
    System.out.println(m.group(1) != null 
        ? "Number: " + m.group(1)  
        : "Non-Number: " + m.group(2));
}

Output:

Non-Number: foo3
Number: 1234
Non-Number: 4bar
Number: 12
Non-Number: 12foo34

edited Jun 21 '13 at 09:51

answered Jun 21 '13 at 09:35

Lukas Eder

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Why not just `\d+|[^,]+`? No need for a capturing group then, a matcher's `.group()` will return the needed value – fge Jun 21 '13 at 09:36
you forgot to exclude whitespaces :p – HamZa Jun 21 '13 at 09:37
@fge: Because then, you know whether a match was a number or a non-number – Lukas Eder Jun 21 '13 at 09:37
1

@HamZa: The OP had no whitespaces in their example – Lukas Eder Jun 21 '13 at 09:37
@LukasEder you know in BOTH cases, see my answer – fge Jun 21 '13 at 09:41
@fge: Point taken. But mine is a regex-only solution – Lukas Eder Jun 21 '13 at 09:43

score 2 · Answer 2 · answered Jun 21 '13 at 09:36

You can use a Scanner:

Scanner sc = new Scanner(input);
sc.useDelimiter(",");
while(sc.hasNext()) {
    if(sc.hasNextInt()) {
        int readInt = sc.nextInt();
        // do something with the int
    } else {
        String readString = sc.next();
        // do something with the String
    }
}

score 1 · Answer 3 · answered Jun 21 '13 at 09:41

Here you go:

        String a = "abc,123,abs12,12ab";
        ArrayList<String> numbers = new ArrayList<>();
        ArrayList<String> letters = new ArrayList<>();
        String ar[] = (a.split(","));
        for (String string : ar) {
            try{
                Long.parseLong(string);
                numbers.add(string);
            }catch(NumberFormatException ex){
                letters.add(string);
            }
        }

Above solution handles the cases where integer digit can be at any location in the string. Not only at the beginning or at the end.

Extract numbers and names from string

3 Answers3