Can this be called using Factory design pattern ?

[Ian Yang]

Suppose I have a super abstract class "Employee" and two subclasses "Worker" and "Manager" that implement some functions defined in "Employee".
I have a "EmployeeFactory" class to generate an instance of either "Worker" or "Manager". it simply takes a parameter variable "title" and do
*******************
public Employee get_Instance(String title) {
Employee e;
if(title.equals("manager"))
e = new Manager();
if(title.equals("worker"))
e = new Worker();
return e;
}
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Can this be called using Factory pattern ? does the method need to handle the case when 'title" is any sort of strange input ?
Thanks,
yang

[Pho Tek]

Ian,
1) You didn't mention whether EmployeeFactory is abstract (which is one of the requirements of the pattern).
2) Also, I believe you'll need two concrete class WorkerFactory and ManagerFactory, both subclassing EmployeeFactory.
Thus you client may look something like this:

Employee e1 = EmployeeFactory.getInstance("Bill Gates", Constants.MANAGER );
Employee e2 = EmployeeFactory.getInstance("Nobody", Constants.WORKER );

3) If somebody passes in some unknown constant, it's better to throw an exception.
Cheers,
Pho

[Christel Veltrup]

Pho, what you describe, is called the Abstract Factory Pattern, I think.
For a plain Factory Pattern, Ian's code seems ok, apart from the fact that getInstance should throw an exception, like you suggested, if the argument is unknown.
The Factory Pattern returns Instances of an abstract type or interface and decides on the actual type from the argument passed to the factory method.
Greetings, Chris

[Pho Tek]

Christel,
You are correct. My apologies for the mix-up.
Thanks
Pho