如何使用Java中的反射查找在类中使用其他接口扩展其他类的所有接口

Question

for example I have:

interface IA;
interface IB;

public class B implements IB;
public class A extends B implements IA;

how can I find in A.class all implemented interfaces in extended B.class too?, method Class<?> getInterfaces() returns only interfaces in A class not in extended class.

Answer 1

Get the superclass and its interfaces

Class<?> clazz = A.class;
Class<?>[] interfaces = clazz.getSuperclass().getInterfaces();
// add interfaces to some larger list

Do this recursively until the superclass is Object or null .

If this Class represents either the Object class, an interface, a primitive type, or void , then null is returned.

Answer 2

You have to loop, calling getInterfaces on A , then use getSuperclass to get its super class, and then do that again, etc., until getSuperclass returns null .

List<Class<?>> list = new LinkedList<Class<?>>();
Class<?> cls = A.class;
while (cls != null) {
    // Call cls.getInterfaces, add result to list
    // ...

    // Go to its parent
    cls = cls.getSuperclass();
}

Answer 3

Guava Solution:

Proxies.java

public static TypeToken.TypeSet getTypes(@Nonnull final Class cls)
{
    return TypeToken.of(cls).getTypes();
}

public static TypeToken subClassesOf(@Nonnull final Class superClass, @Nonnull final Set<TypeToken> typeTokens)
{
    for (final TypeToken tt : typeTokens)
    {
        if (tt.getRawType().getSuperclass() == null)
        {
            return tt;
        }
        {
            return subClassesOf(superClass, tt.getTypes().interfaces());
        }
    }
    return null;
}

Here is how you call it:

    final Class superClass = // super class you want the subclass Interface of
    final TypeToken tt = TypeToken.of(superClass.getClass());
    final TypeToken tti = Proxies.subClassesOf(superClass.getClass(),tt.getTypes().interfaces());
    final Class subTypeInterface = tti.getRawType();

I use this to pull Annotations from a DyanmicProxy instance where the Annotations are on the specialized SubType interface.