Barcode Generator

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int startNum = Integer.parseInt((scanner.nextLine()));
        int finalNum = Integer.parseInt((scanner.nextLine()));

        for (int a = startNum / 1000; a <= finalNum / 1000; a++) {
            for (int b = startNum / 100 % 10; b <= finalNum / 100 % 10; b++) {
                for (int c = startNum / 10 % 10; c <= finalNum / 10 % 10; c++) {
                    for (int d = startNum % 10; d <= finalNum % 10; d++) {
                        if (a % 2 == 1 && b % 2 == 1 && c % 2 == 1 && d % 2 == 1) {
                            System.out.printf("%d%d%d%d ", a, b, c, d);
                        }
                    }
                }
            }
        }
    }
}

ИЛИ:

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String startNum = scanner.nextLine();
        String finalNum = scanner.nextLine();

        for (char a = startNum.charAt(0); a <= finalNum.charAt(0); a++) {
            for (char b = startNum.charAt(1); b <= finalNum.charAt(1); b++) {
                for (char c = startNum.charAt(2); c <= finalNum.charAt(2); c++) {
                    for (char d = startNum.charAt(3); d <= finalNum.charAt(3); d++) {
                        if (a % 2 == 1 && b % 2 == 1 && c % 2 == 1 && d % 2 == 1) {
                            System.out.printf("%c%c%c%c ", a, b, c, d);
                        }
                    }
                }
            }
        }
    }
}