ผู้เชี่ยวชาญช่วยแก้ program java ให้หน่อยฮับ ผมไม่ได้เรียนคอม แต่ดันมีงานตัวนี้ของ java มา

class testAcct2
{
	public static void main(String[] args) 
	{
		//chkAcctNo("111333844516");
		System.out.println(accountCheckDigit("3233443234"));
		  
	}
	public static void chkAcctNo(String acctNo){
		if(acctNo.length()==12){
			int[]digit = new int[13];// variable digit array(12+1)
			int[]chk = new int[13];// variable check array(12+1)
			int sum=0, num; 
			double chkDigit; 
			digit[1] = 12; // digit 1 *12
			digit[2] = 1;  // digit 2 *1
			digit[3] = 10;  // digit 3 *10
			digit[4] = 3;  // digit 4 *3
			digit[5] = 8;  // digit 5 *8
			digit[6] = 5;  // digit 6 *5
			digit[7] = 6;  // digit 7 *6
			digit[8] = 7;  // digit 8 *7
			digit[9] = 4;  // digit 9 *4
			digit[10] = 9;  // digit 10 *9
			digit[11] = 2;  // digit 11 *2
			for(int i=1; i<digit.length; i++){
				String n = acctNo.substring(i-1,i);
				num = Integer.parseInt(n); // convert to Int 
				chk[i] = digit[i]*num;
				sum = sum+chk[i]; 
			}
			System.out.println(sum%11);
			if((sum%11)==0){ // sum%11
				chkDigit = 0; // fraction = 0
			}
			else if((sum%11)<10){ // fraction < 10
				chkDigit = sum%11; // chkDigit = fraction
			}
			else{ // fraction > 9
				System.out.println("invalid check digit, running no "+acctNo); // print 'invalid', running no cannot use
			}
		}
		else{
			System.out.println("ERROR LENGTH");
		}
	}

        public static String accountCheckDigit(String accNumber)
        {
            String errMsg = "";
            int xSum = 0;
            int chkDigit = 0;

            //a[1]*1+a[2]*2+a[3]*3+a[4]*4+a[5]*5+a[6]*6+a[7]*7+a[8]*8+a[9]*9 =  X
            //Y = X mod 11
            //Error message :  Invalid Account Number  

            if (accNumber.length() == 10)
            {
                int j = 1;
                for (int i = 0; i < accNumber.length() ; i++)
                {
                    xSum = xSum +  Integer.parseInt(accNumber.substring(i,1)) * j;
                    j++;
                }
                chkDigit = xSum % 11;
                if (!String.valueOf(chkDigit).equals(accNumber.substring(9, 1)))
                {
                    errMsg = "Error message :  Invalid Account Number";
                }
            }
            else
            {
                errMsg = "Error Message : Account Number Incorrect";
            }
            return errMsg;
        }
}