在JavaFX中使用UI显示和创建枚举的最佳实践是什么？

Question

I have a form with a ComboBox which I'd like to be populated with available values of MyEnum type:

public enum MyEnum {
  FIRST_CHOICE ("First choice"),
  SECOND_CHOICE ("Second choice");

  private String value;

  MyEnum(String value) {
    this.value = value;
  }

  public String toString() {
    return value;
  }
}

myComboBox.getItems().setAll(MyEnum.values());

Then, after making a choice and hitting a button for example, I'd like to create a new MyEnum object. The ideas I came up with are:

Option 1:

Get values from the ComboBox and using switch statement, create a new MyEnum regarding to the choice taken.

Option 2:

Make the String values same as the enumerated ones and create MyEnum using valueOf() :

public enum MyEnum {
  FIRST_CHOICE ("FIRST_CHOICE"),
  SECOND_CHOICE ("FIRST_CHOICE");

  ...
}

MyEnum myEnum = MyEnum.valueOf(myComboBox.getSelectionModel().getSelectedItem())

---------

So the first option is terrible, I know. Second is a bit better but no so user-friendly (since he will see a text like "FIRST_CHOICE") and I suppose there are better options. I'd like to make it in the best possible way, with separation of View and Model as much as I can but I totally don't know how can I achieve that.

Answer 1

I'd go with "option 3", and use the a StringConverter . This will allow you to use enum "under the hood" whilst displaying a more suitable String to the user. This will also allow different strings in different situations, eg internationalization, or different comboboxes on top of same underlying type.

Here I've used a case statement as an example, but could look the value up from properties file etc.

ComboBox<MyEnum> myComboBox = new ComboBox<>();
myComboBox.getItems().setAll(MyEnum.values());
myComboBox.setConverter(new StringConverter<MyEnum>() {

    @Override
    public String toString(MyEnum object) {
        switch (object) {
        case FIRST_CHOICE:
            return "foo";
        case SECOND_CHOICE:
            return "bar";
        default:
            break;
        }
        return null;
    }

    @Override
    public MyEnum fromString(String string) {
        return null;
    }
});

The value returned by the ComboBox will still be of type MyEnum, this can be demonstrated by

myComboBox.valueProperty().addListener((obs, oldValue, newValue) -> {
    System.out.println(myComboBox.getValue());
});

Output

SECOND_CHOICE
FIRST_CHOICE