How to get only the digits from list of string using java

Question

I have list with combination of letters, digits and special characters. I need to extract the digits from string and store them in the same list.

I tried with below code

       List<String> list = new LinkedList<String>();
       list.add("132144, Test");
       list.add("76876295, Test2");
       //tried with replaceAll();
       list.replaceAll(x->x.replace("[^0-9]",""));
       //tried collection
       Collections.replaceAll(list, "\\W+", "");
       System.out.println(list);

Getting the output as [132144, Test,76876295, Test2], need output as [132144,76876295]

Do you want to include the 2 of the text Test2 into the result? — MC Emperor
– MC Emperor, Commented Dec 6, 2019 at 7:24

Elliott Frisch · Accepted Answer · 2019-12-06 05:20:09Z

3

Stream the list, map each entry using a regular expression (\\D matches non-digits) to replace all non-digits with nothing. Collect that back into your original list (assuming you need to keep the new values only). Like,

list = list.stream().map(s -> s.replaceAll("\\D+", ""))
        .collect(Collectors.toList());
System.out.println(list);

Outputs (as requested)

[132144, 768762952]

Your current input doesn't have such a case, but you might also filter out any empty String(s) after applying the regex.

list = list.stream().map(s -> s.replaceAll("\\D+", ""))
        .filter(s -> !s.isEmpty()).collect(Collectors.toList());

answered Dec 6, 2019 at 5:20

Elliott Frisch

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Comments

Soumya Ranjan Swain · Accepted Answer · 2019-12-06 05:22:30Z

0

You can do like this:

    String line = "This order was32354 placed OK?8377jj";
    String regex = "[^\\d]+";

    String[] str = line.split(regex);

    for(int i=0;i<str.length; i++) {
        System.out.println(str[i]);
    }

Output:

32354
8377

Hope this helps.

answered Dec 6, 2019 at 5:22

Soumya Ranjan Swain

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Comments

amol nilwarn · Accepted Answer · 2019-12-06 07:06:28Z

0

public static void main(String[] args) {

    List<String> list = new LinkedList<String>();
    List<String> list1 = new LinkedList<String>();
    list.add("132144, Test");
    list.add("76876295, Test2");
    for(String s:list)
        list1.add(retriveDigits(s));
    System.out.println(list1);
}

private static String retriveDigits(String str) {
    return str.replaceAll("[^0-9]*", "");

}

}

Please find above class, I think that will help you.

answered Dec 6, 2019 at 7:06

amol nilwarn

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Comments

N. berouain · Accepted Answer · 2019-12-06 10:59:41Z

0

you can use NumberUtils.isNumber() in stream like this:

list = list.stream()
           .filter(NumberUtils::isNumber)
           .collect(Collectors.toList());

answered Dec 6, 2019 at 10:59

N. berouain

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