验证手机号的合法性：

public class PhoneNumCheck {
public static void main(String[] args) {
String handset = "18217968050";
System.out.println(check(handset));
}
private static String check(String handset) {
String regex = "^13\\d{9}|15\\d{9}|18\\d{9}$";
if(handset.matches(regex)) {
return handset +"\n 是合法的手机号";
}
return handset + "\n 不是合法的手机号";
}
}