public class ValidateNumberId {

    private static String[]  validtable =  {"1","0","X","9","8","7","6","5","4","3","2"};

    public static boolean cleckIdNumber(String ID){
        boolean flag = false;
        //驗證碼
        String validatecode = ID.substring(17,18);
        //前17位稱為本體碼
        String selfcode = ID.substring(0
 
,17);
        String code[]=new String[17];
        for(int i=0;i<17;i++){
            code[i] = selfcode.substring(i,i+1);
        }
        //加權因子公式：2的n-1次冪除以11取餘數，n就是那個i，從右向左排列。
        int sum = 0;   //用於加權數求和
        for(int i=0;i<code.length;i++){
            //計算該位加權因子
            int yi = adjustmentfactor(i+1
 
)%11;
            //得到對應數位上的數字
            int count = Integer.parseInt(code[code.length-i-1]);
            //加權求和 
            sum +=(count*yi);
        }
        //驗證校驗碼是否正確
        String valdate = validtable[sum%11];
        if(valdate.equalsIgnoreCase(validatecode)) {
            flag = true;
        }
        return
 
 flag;
    }
    /**
    * 計算身份證數位數字加權因子
    * digit表示數位
    */
    public static int adjustmentfactor(int digit){
        int sum = 1;
        for(int i=0;i<digit;i++){
            //sum=sum*2;
            sum=sum<<1;
        }
        return sum;
    }

    public static void main(String[] args) {
        System.out.println(System.currentTimeMillis());
        System.out.println(cleckIdNumber("620321199112302114"));
        System.out.println(System.currentTimeMillis());
    }
}