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I want to do something like this: List<Animal> animals = new ArrayList<Animal>(); for( Class c: list_of_all_classes_available_to_my_app() ) if (c is Animal) animals.add( new c() ); So, I want to look at all of the classes in my application's universe, and when I find one that descends from Animal, I want to create a new object of that type and add it to the list. This allows me to add functionality without having to update a list of things. I can avoid the following: List<Animal> animals = new ArrayList<Animal>(); animals.add( new Dog() ); animals.add( new Cat() ); animals.add( new Donkey() ); ... With the above approach, I can simply create a new class that extends Animal and it'll get picked up automatically. UPDATE: 10/16/2008 9:00 a.m. Pacific Standard Time: This question has generated a lot of great responses -- thank you. From the responses and my research, I've found that what I really want to do is just not possible under Java. There are approaches, such as ddimitrov's ServiceLoader mechanism that can work -- but they are very heavy for what I want, and I believe I simply move the problem from Java code to an external configuration file. Update 5/10/19 (11 years later!) There are now several libraries that can help with this according to @IvanNik's answer org.reflections looks good. Also ClassGraph from @Luke Hutchison's answer looks interesting. There are several more possibilities in the answers as well. Another way to state what I want: a static function in my Animal class finds and instantiates all classes that inherit from Animal -- without any furthe

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