How to extract all numbers from a string?

Question:

I need a way to extract all of the numbers found in a string.

Answer:

Use a regular expression with a pattern matcher.

Code:

import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
public class ExtractNumbers {
   public static void main(String[] args) {
      String str = "This string has numbers 33 and 55 in it.";
      System.out.println(str);
 
      // find 1 or more numbers
      Pattern p = Pattern.compile("[0-9]{1,}");
      Matcher m = p.matcher(str);
 
      while (m.find()) {
         String found = str.substring(m.start(), m.end());
         Integer i = Integer.valueOf(found);
         System.out.println("Found: " + i);
      }
   }
}

Output:

$ java ExtractNumbers 
This string has numbers 33 and 55 in it.
Found: 33
Found: 55