How to remove empty results after splitting with regex in Java?

Question

I want to find all numbers from a given string (all numbers are mixed with letters but are separated by space).I try to split the input String but when check the result array I find that there are a lot of empty Strings, so how to change my split regex to remove this empty spaces?

Pattern reg = Pattern.compile("\\D0*");
String[] numbers = reg.split("asd0085 sa223 9349x");
for(String s:numbers){
    System.out.println(s);
}

And the result:

I know that I can iterate over the array and to remove empty results. But how to do it only with regex?

With Guava, you can do Splitter.onPattern(pattern).omitEmptyStrings().split(string); — dramzy
– dramzy, Commented Aug 24, 2016 at 21:14

Akın Özer · Accepted Answer · 2015-06-23 14:16:44Z

15

If you are using java 8, you can do it in 1 statement like this:

String[] array = Arrays.asList(s1.split("[,]")).stream().filter(str -> !str.isEmpty()).collect(Collectors.toList()).toArray(new String[0]);

answered Jun 23, 2015 at 14:16

Akın Özer

1532 silver badges5 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Bahattin Ungormus Over a year ago

How about Stream.of(s.split(" ")).filter(w -> !w.isEmpty()).toArray(String[]::new);

Pshemo · Accepted Answer · 2016-09-08 17:48:37Z

Don't use split. Use find method which will return all matching substrings. You can do it like

Pattern reg = Pattern.compile("\\d+");
Matcher m = reg.matcher("asd0085 sa223 9349x");
while (m.find())
    System.out.println(m.group());

which will print

0085
223
9349

Based on your regex it seems that your goal is also to remove leading zeroes like in case of 0085. If that is true, you can use regex like 0*(\\d+) and take part matched by group 1 (the one in parenthesis) and let leading zeroes be matched outside of that group.

Pattern reg = Pattern.compile("0*(\\d+)");
Matcher m = reg.matcher("asd0085 sa223 9349x");
while (m.find())
    System.out.println(m.group(1));

Output:

85
223
9349

But if you really want to use split then change "\\D0*" to \\D+0* so you could split on one-or-more non-digits \\D+, not just one non-digit \\D, but with this solution you may need to ignore first empty element in result array (depending if string will start with element which should be split on, or not).

Braj · Accepted Answer · 2014-08-22 16:18:35Z

2

You can try with Pattern and Matcher as well.

Pattern p = Pattern.compile("\\d+");
Matcher m = p.matcher("asd0085 sa223 9349x");
while (m.find()) {
    System.out.println(m.group());
}

answered Aug 22, 2014 at 16:18

Braj

46.9k5 gold badges63 silver badges77 bronze badges

Comments

Rakesh KR · Accepted Answer · 2014-08-22 16:22:23Z

2

The method i think to solve this problem is,

String urStr = "asd0085   sa223 9349x";
urStr = urStr.replaceAll("[a-zA-Z]", "");
String[] urStrAry = urStr.split("\\s");

Replace all alphabets from the string.
Then split it by whitespace (\\s).

answered Aug 22, 2014 at 16:22

Rakesh KR

6,5475 gold badges45 silver badges58 bronze badges

Comments

deamon · Accepted Answer · 2014-08-22 16:18:43Z

1

Pattern reg = Pattern.compile("\\D+");
// ...

results in:

0085
223
9349

answered Aug 22, 2014 at 16:18

deamon

93.1k117 gold badges332 silver badges461 bronze badges

Comments

Rahul Tripathi · Accepted Answer · 2014-08-22 16:18:48Z

1

You may try this:

reg.split("asd0085 sa223 9349x").replace("^/", "")

answered Aug 22, 2014 at 16:18

Rahul Tripathi

173k33 gold badges292 silver badges341 bronze badges

Comments

Rohit Jain · Accepted Answer · 2014-08-22 16:22:27Z

Using String.split(), you get an empty string as array element, when you have back to back delimiter in your string, on which you're splitting.

For e.g, if you split xyyz on y, the 2nd element will be an empty string. To avoid that, you can just add a quantifier to delimiter - y+, so that split happens on 1 or more iteration.

In your case it happens because you've used \\D0* which will match each non-digit character, and split on that. Thus you've back to back delimiter. You can of course use surrounding quantifier here:

Pattern reg = Pattern.compile("(\\D0*)+");

But what you really need is: \\D+0* there.

However, if what you only want is the numeric sequence from your string, I would use Matcher#find() method instead, with \\d+ as regex.

Collectives™ on Stack Overflow

How to remove empty results after splitting with regex in Java?

7 Answers 7

1 Comment

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

7 Answers 7

1 Comment

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related