Question

I am designing a virtual aquarium. I have a class: Fish which I inherit to create classes of different species. The user can select the species in a combo box and click a button to put the fish in the tank. I use the following code to create the fish:

    switch(s){
        case "Keegan" :
            stock.add(new Keegan(this, x,y));
            break;
        case "GoldenBarb" :
            stock.add(new GoldenBarb(this, x,y));

“stock” is a LinkedList and “s” is the String selected in the Jcombobox. As it stands I will have to create a long switch when I add a bunch of different species. I would like the code to look like:

stock.add(new s(this,x,y));

and dispense with the switch such that all I have to do is create the class and add its name to the combo box and have it work. Is there a way to do so? Any help is appreciated.

Answer 1

I think reflection might be what you are looking for. This allows you to avoid the switch statement, which is what you are asking.

Reflection (among other things) allows you to run methods with just strings. So in Java, where you would normally call a method like this:

new Foo().hello();

With Reflection, you can use a string to call the method, like this:

Class<?> clazz = Class.forName("Foo");
clazz.getMethod("hello").invoke(clazz.newInstance());

Java Constructor Reflection example.

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Regarding the Factory pattern (referring now to other answers), as I understand it, that is just encapsulating the switch statement (or whatever method you choose to use). The Factory pattern itself is not a means of avoiding the switch statement. The Factory Pattern is a good thing, but not what you were asking. (You will probably want to use the factory pattern in any case).