sort

In my driver.java I have the code bellow.

public static void disSortedDepartment()
{
         Vector dept = cpn.getDepartments();
                   
         if(dept.isEmpty())
         {
               System.out.println("There is no departments in the company");
         }
         else
         {
                 Collections.sort(dept);
                       
       Iterator iter = dept.iterator();
                       
       while(iter.hasNext())
       {
          Department d = (Department) iter.next();
          System.out.println(d);
                 }
           }        
 }


In my department.java I have the following code:

public int compareTo(Object obj)
{
         if(this==obj)
         {
                  return 0;
         }
                  
         if(!(obj instanceof Department))
         {
                return 0;
         }
                  
         Department d = (Department) obj;
                  
        return this.getDepartmentName().compareTo(d.getDepartmentName());
}

The code seems to be right, but when I try to run it I am getting an exception error.

How do I solve the problem?

You can download the code from:

www.mutaiyas.com/db/Employee.zip

Your help is kindly appreciated.

Regards

Eugene