Verification code algorithm verification for ID card verification

Import java. util. calendar; import java. util. secret; public class ValidateID {public static void main (String [] args) {ValidateID vid = new ValidateID (); System. out. println ("Enter the ID number:"); then SC = new then (System. in); String id = SC. nextLine (); vid. validateLastNum (id);}/** this algorithm can basically filter all non-conforming id cards. ** the algorithm for the last digit verification code of the id card number is as follows: SIGMA (a [I] * W [I]) mod 11 (I = 2, 3 ,..., 18) "*": * indicates the number of each digit of the ID card number, from right to left, 18 at the left, and The right side is 1. A [I]: indicates the ID number on the I-digit number W [I]: indicates the weight on the * I-digit W [I] = 2 ^ (I-1) mod 11: R = Σ (a [I] * W [I]) mod 11 (I = 2, 3 ,..., * 18) C = ID card number verification code, the relationship between R and C is as follows: R: 0 1 2 3 4 5 6 7 8 9 10 C: 1 0X9 8 7*6 5 4 3 2 from this we can see that X is 10, and 10 of the Roman numerals is X. Therefore, the new standard ID card number may contain non-numeric letters X. */Public boolean validateLastNum (String strId) {// determines whether the ID card is 18-bit if (strId. length ()! = 18) {return false;} // String is converted to StringBuffer to use the reverse () method StringBuffer sb = new StringBuffer (strId); // String reverse sb. reverse (); // returns to facilitate the operation of String id = new String (sb); // if it contains non-numbers, return false directly to exit try {Long. parseLong (id);} catch (Exception e) {// System. out. println ("this string can only be a number"); return false;} // The following algorithm follows the formula int sum = 0; int C = 0; int [] W = new int [17]; int [] a = new int [17]; for (int I = 2; I <19; I ++) {W [I-2] = (Int) (Math. pow (2, I-1) % 11); a [I-2] = Integer. parseInt (id. substring (I-1, I); sum + = (a [I-2] * W [I-2]);} int R = sum % 11; // according to the R: C correspondence, convert if (R = 0) {C = 1;} if (R = 1) {C = 0 ;}if (R = 2) {C = 10 ;}if (R> 2) {C = 12-R ;}// intercept the first character, that is, the last character String lastChar = id before conversion. substring (0, 1); // converts the truncated characters into numbers int lastNum = Integer. parseInt (lastChar); // compare the last character of the ID card with the calculated data. if the characters are equal, the result is correct. if the characters are incorrect (LastNum! = C) {// Since R = 2 corresponds to C = 10, 10 represents X in the ID card, therefore, you can determine if (C = 10 & lastChar. equals ("X") {// System. out. println ("ID card verification code"); return true;} // System. out. println ("ID card verification failed"); return false;} // System. out. println ("ID card verification code"); return true ;}}