新的Object.getClass（）

Question

Is there a way to make a new Object of the type of another?

Example:

Soldier extends Person
Accountant extends Person

Each subclass of Person has a constructor that accepts (BirthDate and DeathDate)

I have a method called prepPerson(Person) and it accepts a Person. I would like to have a JComboBox populated with Person objects of different types (Accountant, Soldier) that I call .getSelectedItem() and get back a Person object.

As I am only using those Person objects to populate the JComboBox menu how do I detect the type of person selected, make a new Soldier or Accountant object so that I can pass it to the prepPerson method?

Answer 1

Use either instanceof or create method getType() on Person which return enum - the type of the Person .

But when you start using instanceof in such situation you may consider to change the desing somehow.

Could you describe why do you need to distinguish them later?

Answer 2

If you're going to have a finite number of selections, do this:

Person thePerson = null; // note, don't call variables theAnything... it's just bad

JComboBox theBox = new JComboBox(new String[]{"Accountant","Soldier","Programmer"});



// later

public void actionPerformed(ActionEvent e) {
        if(e.getSource() == theBox) {
            String who = (String)theBox.getSelectedItem();
            if(who.equals("Accountant") thePerson = new Accountant();
            if(who.equals("Soldier") thePerson = new Soldier();
            if(who.equals("Programmer") thePerson = new Programmer();
        }
}

Answer 3

Why do you need to detect the type? You have a Person and you must pass a Person to the new method.

You are likely to find seperating Roles/Types from a Person useful. This way any Person can have one or more roles which can change at any time.