Multiply Big Number

package TechFundamentals;

import java.util.*;


public class array_temp {


    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        String oneInput = scanner.next();
        int two = scanner.nextInt();
        int numZero = 0;
        boolean zero = true;
        if (oneInput.length() > 1) {
            String num = "" + oneInput.charAt(0);
            numZero = Integer.parseInt(num);
            zero = false;
        }

        if ( two == 0) {
            System.out.println("0");
        } else {
            int index = 0;
            for (int i = 0; i < oneInput.length() - 1; i++) {
                String tempStr = oneInput.charAt(i) + "";
                int num = Integer.parseInt(tempStr);
                boolean checkZero = true;
                if (i == 0 && num == 0) {
                    checkZero = false;
                }
                if (!checkZero) {
                    for (int j = i + 1; j < oneInput.length(); j++) {

                        if (num == 0 && j != 0) {
                            index = j;
                        }
                    }
                }
            }


            StringBuilder sb = new StringBuilder();
            int tempNum = 0;

            for (int i = oneInput.length() - 1; i >= index; i--) {
                String tempStr = oneInput.charAt(i) + "";
                int num = Integer.parseInt(tempStr);

                int sum = tempNum + num * two;
                if (sum > 9) {
                    int numberHight = sum % 10;
                    sb.append(numberHight);
                    tempNum = sum / 10;

                } else {
                    sb.append(sum);
                    tempNum = 0;
                }

            }

            if (tempNum != 0) {
                sb.append(tempNum);
            }
            sb.reverse();
            System.out.println(sb.toString());
        }




    }


}