An example of java multithreading; 2 cashiers attending one client each one simultaneously

ThreadedCashier.java

public class ThreadedCashier {

    public static void main(String[] args) {

        Client client1 = new Client("Client 1", new int[]{2, 2, 1, 5, 2, 3, 1, 6, 1, 2, 1, 5});
        Client client2 = new Client("Client 2", new int[]{1, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 2});

        long initialTime = System.currentTimeMillis();
        Cashier cashier1 = new Cashier("Cashier 1", client1, initialTime);
        Cashier cashier2 = new Cashier("Cashier 2", client2, initialTime);

        System.out.println("OPEN DOORS");
        cashier1.start();
        cashier2.start();
        try {
            cashier1.join();
            cashier1.join();
        } catch (InterruptedException ex) {
        }
        System.out.println("CLOSE DOORS");
    }
}

class Cashier extends Thread {

    private String cashierName;

    public String getCashierName() {
        return cashierName;
    }
    private Client currentClient;

    public Client getCurrentClient() {
        return currentClient;
    }
    private long initialTime;

    public Cashier(String name, Client cli, long time) {
        cashierName = name;
        currentClient = cli;
        initialTime = time;
    }

    @Override
    public void run() {

        System.out.println(this.cashierName + " START PROCESSING "
                + this.currentClient.getClientName() + " TIME: "
                + (System.currentTimeMillis() - this.initialTime) / 1000
                + "SEC");

        for (int i = 0; i < this.currentClient.getBuyBox().length; i++) {
            this.waitSeconds(currentClient.getBuyBox()[i]);
            System.out.println(this.cashierName + " PROCESSED " + (i + 1)
                    + " OF " + this.currentClient.getClientName() + " TIME: "
                    + (System.currentTimeMillis() - this.initialTime) / 1000
                    + "SEC");
        }

        System.out.println(this.cashierName + " ENDS WITH "
                + this.currentClient.getClientName() + " TIME: "
                + (System.currentTimeMillis() - this.initialTime) / 1000
                + "SEC");
    }

    private void waitSeconds(int segundos) {
        try {
            Thread.sleep(segundos * 1000);
        } catch (InterruptedException ex) {
            Thread.currentThread().interrupt();
        }
    }
}

class Client {

    private String clientName;

    public String getClientName() {
        return clientName;
    }

    public int[] getBuyBox() {
        return buyBox;
    }
    private int[] buyBox;

    public Client(String name, int[] box) {
        clientName = name;
        buyBox = box;
    }
}