字符串中找出连续最长的数字串

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

public class Main{

     static final String reg = "[0-9]+";
     static Pattern pattern = Pattern.compile(reg);


    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        String maxStr = maxLengthNum(in.next());
        System.out.println(maxStr);
    }

    public static String maxLengthNum(String str){
        Matcher matcher = pattern.matcher(str);
        String maxStr = "";
        int maxLen = 0;
        String tempStr = "";
        while(matcher.find()){
            tempStr = matcher.group();
            if(tempStr.length() > maxLen){
                maxLen = tempStr.length();
                maxStr = tempStr;
            }
        }
        return maxStr;
    }
}