判断是否整除 Java java判断是否为正整数

public static boolean isPureDigital(String str) {
		if (str == null || "".equals(str)){
			return false;
		}
		String regEx1 = "^[1-9]\d*$";
		Pattern p;
		Matcher m;
		p = Pattern.compile(regEx1);
		m = p.matcher(string);
		if (m.matches()){
			return true;
		}else{
			return false;
			}
	}