A better way to use Java Enum than switch

I think java enum are a nice addition to the language. I used to combine them with switch/case statements. But lately François, a colleague, shown we a better way :)

You can embedded behavior in each enumeration case, reducing client code and making it more elegant :)

Let's take a simple example: Every day of the week you need to do something: take out the garbage, go to the laundry etc. ...

Using switch here's how I would have done it:

    private enum Week {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday}
    
    public static void main(String[] args) {
        final Week today = getToday();
        Action action;
        switch (today) {
            case Sunday:
                action = new FamillyDiner();
                break;
            case Monday:
            case Friday:
                action = new Garbage();
                break;
            case Tuesday:
                action = new Laundry();
                break;
            case Wednesday:
                action = new ChillOut();
                break;
            case Thursday:
                action = new Grocery();
                break;
            case Saturday:
                action = new SoccerGame();
                break;
            default:
                throw new RuntimeException("Impossible day!");
        }
        action.execute();
    }

Conclusion:

• You can see the number of lines in main() is quite important
• The client code (the switch/case code) is likely to be duplicate
• There is an unnecessary case "default" that can never happen (even null case would result in a NullPointerException in the switch)
• But it still much better than a if/elseif/else using int

Adding behavior to the enum:

    private enum Week {
        Sunday {
           @Override
            public void execute() {
                System.out.println("Mom and Dad diner.");
            } 
        }, Monday {
            @Override
            public void execute() {
                System.out.println("Take the garbage out.");
            } 
        }, Tuesday {
            @Override
            public void execute() {
                System.out.println("Do the laundry.");
            } 
        }, Wednesday {
            @Override
            public void execute() {
                System.out.println("Have a beer. Just Chill out!");
            } 
        }, Thursday {
            @Override
            public void execute() {
                System.out.println("Go out to the local store for Grocery with shoping list.");
            } 
        }, Friday {
            @Override
            public void execute() {
                System.out.println("Take the garbage out.");
            } 
        }, Saturday {
            @Override
            public void execute() {
                System.out.println("Manchester vs Arsenal! Can't miss that!");
            } 
        };
        
        public abstract void execute();
    }
    
    public static void main(String[] args) {
        final Week today = getToday();
        today.execute();
    }

Conclusion:

• Less lines of code and still readable
• main() code is soooo easy
• No unnecessary case "default"
• If you don't want this behavior and still use the enum you are free to use the switch/case way

Clearly I think this approach is far better and much more elegant unless someone show me otherwise...

Download the complete code sample.