Question

I want to do something like this:

public class MyEnumTest {

    public enum MyEnum;
    private MyEnum value;

    public MyEnumTest(enum e)
    {
        this.MyEnum = e; 
        this.value = this.MyEnum.values[0]//Set value to the first enum value.
    }

    public void setValue(MyEnum e)
    {
        this.value = e; 
    }

    public MyEnum getValue()
    {
        return value;
    }

}

and call it something like this:

MyEnumTest car = new MyEnumTest({HONDA, FORD, TOYOTA, HOLDEN}); 
MyEnumTest fruit = new MyEnumTest({APPLE, BANANA, CHERRY}); 

/* some operations occur*/ 

if (car.getValue() == car.FORD) System.out.println("Vrooom!"); 
if (fruit.getValue()) == fruit.APPLE) System.out.println ("Is red and round and delicious"); 

Any ideas for doing this?

For bonus marks – would it be possible to set the initial value using the enum values?
eg something like

MyEnumTest myET = new myEnumTest(new enum {RED, GREEN, BLUE, YELLOW}, BLUE); 

Answer 1

As others said it’s hard to understand what you are trying to do, but here is my best guess:

public enum Color {
    RED, GREEN, YELLOW, BLUE;
}


public class MyEnumTest<E extends Enum<E>> {
    private final Class<E> enumType;
    private final E value; 

    public Class<E> getEnumType() {
        return enumType;
    }

    public E getValue() {
        return value;
    }

    public MyEnumTest(Class<E> enumType, E value) {
        this.enumType = enumType;
        this.value = value;
    }

    public MyEnumTest(Class<E> enumType) {
        this(enumType, enumType.getEnumConstants()[0]);
    }

    public static void main(String... args) {
        // no initial value provided
        MyEnumTest<Color> myET = new MyEnumTest<Color>(Color.class);
        if (myET.getValue() == Color.RED) {
            System.out.println("It's probably an apple");
        }

        // providing an initial value
        myET = new MyEnumTest<Color>(Color.class, Color.YELLOW);
        if (myET.getValue() == Color.YELLOW) {
            System.out.println("It's probably a banana");
        }
    }
}

Also, keep in mind that enum values are static… So, something like myET.MyEnum.RED doesn’t make sense… You should use instead: Color.RED