java - get all (derived) interfaces of a class

Question

java.lang.Class.getInterfaces returns all directly implemented interfaces ie doesn't walk the class tree to get all interfaces of all parent types. eg For example the hierarchy

public interface A {}
public interface B {}
public interface C extends B {}

public class Foo implements A {} // Foo.class.getInterfaces() returns [A]
public class Bar implements C {} // Bar.class.getInterfaces() returns [C], note B is not included.

For Bar I would like to get [B, C], but for any arbitrary tree depth.

I could write this myself, but I'm sure a library must exist that does this already, any ideas?

Answer 1

Apache Commons Lang has method you need: ClassUtils.getAllInterfaces