test.java

    public int generateValidPinCode(String seed) {
        int pin = 0;
        Random r = new Random(System.nanoTime() + seed.hashCode());
        int randombit = r.nextInt(9) * 1000 + r.nextInt(999);

        ResultSet results = sqlDatabase.executeQuery("SELECT * FROM warnings WHERE pin=?", randombit);
        try {
            if (results.next()) {
                pin = generateValidPinCode(Integer.toString(randombit));
            } else {
                pin = randombit;
            }
        } catch (SQLException e) {
            pin = randombit;
        }
        return pin;
    }