Java - Write code to get First Positive Number using regex

Requirements

Write code to get First Positive Number using regex

Demo

//package com.book2s;

import java.util.StringTokenizer;

public class Main {
    public static void main(String[] argv) {
        String string = "wer 234 book2s.com";
        System.out.println(getFirstPositiveNumber(string));
    }/*w  w  w . jav a  2s.  c  o m*/

    public static String getFirstPositiveNumber(String string) {
        if (isEmpty(string)) {
            return "";
        }

        String[] numbers = string.split("([^\\d]+)");

        if (numbers.length > 0) {
            return numbers[0];
        }

        return "";
    }

    public static boolean isEmpty(String str) {
        int strLen;
        if (str == null || (strLen = str.length()) == 0) {
            return true;
        }

        for (int i = 0; i < strLen; i++) {
            if (Character.isWhitespace(str.charAt(i)) == false) {
                return false;
            }
        }

        return true;
    }

    public static String[] split(String str, String delim) {
        return split(str, delim, true, false);
    }

    public static String[] split(String str, String delim, boolean trim,
            boolean include) {
        StringTokenizer tokens = new StringTokenizer(str, delim, include);
        String[] result = new String[tokens.countTokens()];
        int i = 0;
        while (tokens.hasMoreTokens()) {
            String token = tokens.nextToken();
            if (trim) {
                token = token.trim();
            }
            result[i++] = token;
        }
        return result;
    }
}