Question

I have a String variable (basically an English sentence with an unspecified number of numbers) and I’d like to extract all the numbers into an array of integers. I was wondering whether there was a quick solution with regular expressions?

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I used Sean’s solution and changed it slightly:

LinkedList<String> numbers = new LinkedList<String>();

Pattern p = Pattern.compile("\\d+");
Matcher m = p.matcher(line); 
while (m.find()) {
   numbers.add(m.group());
}

Answer 1

Pattern p = Pattern.compile("-?\\d+");
Matcher m = p.matcher("There are more than -2 and less than 12 numbers here");
while (m.find()) {
  System.out.println(m.group());
}

… prints -2 and 12.

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-? matches a leading negative sign — optionally. \d matches a digit, and we need to write \ as \\ in a Java String though. So, \d+ matches 1 or more digits.