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

The most robust mechanism for listing all subclasses of a given class is currently ClassGraph, because it handles the widest possible array of classpath specification mechanisms, including the new JPMS module system. (I am the author.)

List> animals;
try (ScanResult scanResult = new ClassGraph().whitelistPackages("com.zoo.animals")
        .enableClassInfo().scan()) {
    animals = scanResult
        .getSubclasses(Animal.class.getName())
        .loadClasses(Animal.class);
}