Barcode Generator

package com.company;

import java.util.Scanner;

public class Main {

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

        int num1 = Integer.parseInt(scan.nextLine());
        int num2 = Integer.parseInt(scan.nextLine());

        int endNum = 0;
        String numStr = "";

        int thousands1 = num1 / 1000;
        num1 %= 1000;
        int copyTh1 = thousands1;
        int hundreds1 = num1 / 100;
        num1 %= 100;
        int copyHu1 = hundreds1;
        int tens1 = num1 / 10;
        int copyTe1 = tens1;
        int ones1 = num1 % 10;
        int copyOn1 = ones1;

        int thousands2 = num2 / 1000;
        num2 %= 1000;
        int hundreds2 = num2 / 100;
        num2 %= 100;
        int tens2 = num2 / 10;
        int ones2 = num2 % 10;

        if (thousands2 % 2 == 0) thousands2--;
        if (hundreds2 % 2 == 0) hundreds2--;
        if (tens2 % 2 == 0) tens2--;
        if (ones2 % 2 == 0) ones2--;

        endNum = Integer.parseInt("" + thousands2 + hundreds2 + tens2 + ones2);

        while (num1 < endNum) {

            if (thousands1 < thousands2 && thousands1 % 2 == 0) thousands1++;
            if (hundreds1 < hundreds2 && hundreds1 % 2 == 0) hundreds1++;
            if (tens1 < tens2 && tens1 % 2 == 0) tens1++;
            if (ones1 < ones2 && ones1 % 2 == 0) ones1++;

            numStr = "" + thousands1 + hundreds1 + tens1 + ones1;
            System.out.print(numStr + " ");

            ones1 += 2;

            if(ones1 > ones2){
                ones1 = copyOn1;
                tens1 += 2;
                if(tens1 > tens2){
                    tens1 = copyTe1;
                    hundreds1 += 2;
                }
                if(hundreds1 > hundreds2){
                    hundreds1 = copyHu1;
                    thousands1 += 2;
                }
            }
            num1 = Integer.parseInt(numStr);
        }
    }
}