如何从接口获取实现该接口的类的枚举？

Question

I am trying to get an enum from this interface:

public interface PizzaInterface {
    public enum Toppings {
        pepperoni, sausage, mushrooms, onions, greenPeppers;
    }
}

to this class:

public class Pizza implements PizzaInterface{
    private String[] toppings = new String[5];
}

and be able to store it in the array.

(edit): I want to put it in a ArrayList if that changes anything.

Answer 1

The first thing you need to understand is that Enum will be static inside that Interface. And call to values() method on any enum will return the array of enums instances. So if you can work with Enum array rather than String, you should be using that values() call like the way pbabcdefp mentioned above. :

PizzaInterface.Toppings[] toppings = PizzaInterface.Toppings.values();

But if you need String contents, I would like to suggest you to use ArrayList. There are usually more benefits using ArrayList then to Arrays. In that case , If I were you, I would add one static method inside the Enum class to return the list of strings, which I would have used in the Pizza class. Sample code would be like :

public interface PizzaInterface {
public enum Toppings {
    pepperoni, sausage, mushrooms, onions, greenPeppers;

   public static List<String> getList(){
       List<String> toppings=new ArrayList<String>();
       for (Toppings topping:Toppings.values() ){
           toppings.add(topping.name());
       }
       return toppings;
   }
}

}

and

public class Pizza implements PizzaInterface{
   private static List<String> toppings = PizzaInterface.Toppings.getList();
//use the toppings list as you want

}

Answer 2

Why do you want a String[] ? A Toppings[] would be better. You can do this with

PizzaInterface.Toppings[] toppings = PizzaInterface.Toppings.values();

Answer 3

If you want to store your values as Strings you can do this:

       private String[] toppings = names();

        public static String[] names() {
            Toppings[] toppings = PizzaInterface.Toppings.values();
            String[] names = new String[toppings.length];

            for (int i = 0; i < toppings.length; i++) {
                names[i] = toppings[i].name();
            }

            return names;
        }

otherwise just call the .values() method from your enum and you will get a array of Toppings

PizzaInterface..Toppings.values();