Iterator pattern - Example

Employee is an interface. Manager, PieceWorker, HourlyWorker and CommissionWorker are implementation classes of interface Employee. 

EmployeeTest class will create a list and use a built-in iterator of ArrayList class to traverse the members of the list.

interface Employee {   

    public abstract double earnings();

}

class Manager implements Employee { .... }

class PieceWorker implements Employee { .... }

class HourlyWorker implements Employee { .... }

class CommissionWorker implements Employee { .... }

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java.util.List list = new ArrayList();

list.add(new Manager("Bill", 800.00));

list.add(new CommissionWorker("Newt", 400.0, 3.75, 159.99));

list.add(new PieceWorker("Al", 2.5, 200));

list.add(new HourlyWorker("Babara", 13.75, 40));

list.add(new Manager("Peter", 1200.00));

list.add(new CommissionWorker("Margret", 600.0,5.5, 200.25));

list.add(new PieceWorker("Mark", 4.5, 333));

list.add(new HourlyWorker("William", 31.25, 50));

    

System.out.println("Use built-in iterator:");

Iterator iterator = list.iterator();

while(iterator.hasNext()) {

  Employee em = (Employee)iterator.next();

  System.out.print(em + " earns $");

  System.out.println(em.earnings());

}