Hide the middle digit of ID number

I met a problem when writing Alipay applet today , ID number needs to be hidden , Do the following ：

String s = "37011219810228316X";
String a = "";
if (s.endsWith("X") || s.endsWith("x")){
    
    a = s.substring(0,1)+"****************X";
}else {
    
    a = s.replaceAll("(\\d{1})\\d{16}(\\d{1})", "$1****************$2");
}
System.out.println(a);

The output is as follows ：

3****************X

ID number is divided into two categories , Class I contains ‘X’ Character , A kind of pure digital . Pure numbers can be regularized , contain ’X’ Characters are not good .