正则表达式

^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$

^1[3-9]\d{9}$

^[1-9]\d{5}(18|19|20)\d{2}(0[1-9]|1[0-2])(0[1-9]|[12]\d|3[01])\d{3}[\dXx]$

^[A-Za-z0-9]{6,12}$

^(?=.*[a-z])(?=.*[A-Z])(?=.*\d)[A-Za-z\d]{6,16}$

^(https?://)?([a-zA-Z0-9.-]+)(:[0-9]{1,5})?(/.*)?$

String regex = "^1[3-9]\\d{9}$";
boolean isValid = Pattern.matches(regex, "13812345678");

Pattern pattern = Pattern.compile("\\d+");
Matcher matcher = pattern.matcher("abc123xyz456");
while (matcher.find()) {
    System.out.println(matcher.group()); // 输出 123 和 456
}