Java string comparator that sorts numbers within the strings as complete numbers rather than character by character.

NumberAwareStringComparator.java

import java.util.Comparator;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class NumberAwareStringComparator implements Comparator<String> {

  private static final Pattern splitter = Pattern.compile("([-]?[\\d]+(?:\\.[\\d]+)?|[\\D]+)");
  private static final Pattern matchNumber = Pattern.compile("[-]?\\d+(?:\\.[\\d]+)?");

  @Override
  public int compare(String s1, String s2) {
    if(s1.equals(s2)) return 0;
    
    Matcher m1 = splitter.matcher(s1);
    Matcher m2 = splitter.matcher(s2);
    
    while(m1.find() && m2.find()) {
      if(matchNumber.matcher(m1.group()).matches() && matchNumber.matcher(m2.group()).matches()) {
        int numberCompareResult = Double.compare(Double.parseDouble(m1.group()), Double.parseDouble(m2.group()));
        if(numberCompareResult != 0) return numberCompareResult ;
      }
      else {
        if(m1.group().compareTo(m2.group()) != 0) return m1.group().compareTo(m2.group());
      }
    }
    return m1.matches() ? 1 : (m2.matches() ? -1 : 0);
  }

}