At runtime, find all classes in a Java application that extend a base class

Question

I want to do something like this:

List animals = new ArrayList();

for( Class c: list_of_all_classes_available_to_my_app() )
   i         


        

Answer 1

I use org.reflections:

Reflections reflections = new Reflections("com.mycompany");    
Set> classes = reflections.getSubTypesOf(MyInterface.class);

Another example:

public static void main(String[] args) throws IllegalAccessException, InstantiationException {
    Reflections reflections = new Reflections("java.util");
    Set> classes = reflections.getSubTypesOf(java.util.List.class);
    for (Class aClass : classes) {
        System.out.println(aClass.getName());
        if(aClass == ArrayList.class) {
            List list = aClass.newInstance();
            list.add("test");
            System.out.println(list.getClass().getName() + ": " + list.size());
        }
    }
}