java-reflection-get-classes.md

title: Java: Get all classes in a package via reflection tags: java,java-reflection

If you use the excellent Reflections java library, you can do this easily enough:

	Reflections reflections = new Reflections("Your.package.name");
	Set<Class<? extends Action>> classes = reflections.getSubTypesOf(YourClass.class);
	for (Class<? extends Action> class : classes) {
		try {
			YourClass your = class.newInstance();
		} catch (Exception e) {
			e.printStackTrace();
		} 
	}

Here you specify the package and the classtype that the classes must either extend or implement.

You throw an exception if you try to make a new instance of a class that's freaky for some reason - no null arg constructor for example.