JAVA判断字符串为数字且长度固定

private static void isFixedNumeric() {
	String regex="\d{6}";
	String target="023300";
	Pattern pattern=Pattern.compile(regex);
	boolean matches = pattern.matcher(target).matches();
	System.out.println(matches);
}

判断字符串长度是否为6的数字字符串