Enum vs If-else

Question

I have a requirement wherein I need to build an employee object as below from an event list. Currently I've written my code as below, but QE gave a comment saying possible use of enums instead of multiple if else's. Can someone suggest me on how to achieve this with enums.

Employee e= new Employee();
for(Event event:events){
if("empid".equals(event.getName())
   e.setEmployeeId(event.getvalue());
else if("empname".equals(event.getName())
   e.setEmployeeName(event.getvalue());
else if("empsal".equals(event.getName())
   e.setEmployeeSal(event.getvalue());
else if("empdob".equals(event.getName())
   e.setEmployeeDOB(event.getvalue());
else if("emprole".equals(event.getName())
   e.setEmployeeRole(event.getvalue());
}

Answer 1

If you are in control of development of Event, I believe what your QE saying is to replace event name by an enum (which is a sane design as you have already decide what is the possible types of event). However, if Event's design is out of your control, or you cannot have a child class of Event for your use (e.g. make an EmployeeEvent), then just ignore what I am going to say)

i.e.

enum EventType {
    EMP_ID,
    EMP_NAME,
    ....
}


interface Event {
    EventType getType();   // instead of getName() which returns a String
}

Then your code can be simplified to

Employee e= new Employee();
for (Event event: events) {
    switch (event.getType()) {
        case EMP_ID:
            e.setEmployeeId(event.getvalue());
            break;
        case EMP_NAME:
            e.setEmployeeName(event.getvalue());
            break;
        ....
    }
}

You may even preset the action to do against each event type, using a map (which is of similar idea of another answer)

Map<EventType, BiConsumer<Employee, String>> eventActions = new EnumMap<>();
eventActions.put(EventType.EMPLOYEE_ID, Employee::setEmployeeID);
eventActions.put(EventType.EMPLOYEE_NAME, Employee::setEmployeeName);

so you can further simplify the above switch by:

Employee e= new Employee();
for (Event event: events) {
    eventActions.get(event.getType()).accept(e, event.getValue()));
}