ServiveOffice, Employee class

package ServicePkg;

public class Employee extends Thread {
    private static int employeeCounter = 0;

    private String employeeName;
    private Office myOffice;

    private boolean isWorking;

    public Employee(Office myOffice) {
        Employee.employeeCounter += 1;
        this.employeeName = "Employee #" + Employee.employeeCounter;

        this.myOffice = myOffice;
        isWorking = false;
    }

    public String getEmployeeName() {
        return this.employeeName;
    }

    public boolean isWorking() {
        return this.isWorking;
    }

    public void startWorking() {
        if (!isWorking) {
            isWorking = true;
            start();

            Utils.printLog("Working: " + employeeName + " start to work.");
        }
    }

    public synchronized void stopWorking() {
        isWorking = false;
        if (isWaiting()) {
            stopWaiting();
        }
    }

    public synchronized boolean isWaiting() {
        return getState() == Thread.State.WAITING;
    }

    public void stopWaiting() {
        if (isWaiting()) {
            synchronized (this) {
                notify();
            }
        }
    }

    @Override
    public void run() {
        while (isWorking) {
            Utils.printLog("Calling: " + this.employeeName
                    + " is calling for customer.");
            Customer customer = this.myOffice.getNextCustomer();
            if (customer != null) {
                int serviceTime = Utils.getRandomServiceTime();
                Utils.printLog("Served : " + customer
                        + " started to get service from " + this.employeeName
                        + " for " + serviceTime + "ms");

                try {
                    Thread.sleep(serviceTime);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                Utils.printLog("EndSrv : " + customer + " has finished. "
                        + this.employeeName + " is free.");

            } else if (myOffice.isOpen()) {

                // waiting for customers
                synchronized (this) {
                    try {
                        wait();
                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }

            } else {
                this.stopWorking();
            }

        }
        Utils.printLog("No Work: " + this.employeeName + " stop working.");
    }

    @Override
    public String toString() {

        return this.employeeName;
    }

}