java 将数字替换成下划线

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexDemo {
    public static void main(String[] args) {
        String str="A1B22C333D4444E55555";
        String pat="\\d+";
        Pattern p=Pattern.compile(pat);
        Matcher m=p.matcher(str);
        String newS=m.replaceAll("_");
        System.out.print(newS);
    }
}