Get Actual Type Generic Argument

getActualTypeArgument

public static Type getActualTypeArgument(Type type, Class topClass) {

        if (type instanceof TypeVariable) {

            TypeVariable typeVariable = (TypeVariable) type;
            Class declareClass = topClass;

            // find declare class
            while (declareClass != null) {
                if (((ParameterizedType) declareClass.getGenericSuperclass()).getRawType() == typeVariable.getGenericDeclaration()) {
                    break;
                }
                declareClass = declareClass.getSuperclass();
            }

            if (declareClass != null) {
                int index = -1;
                int internalIndex = 0;
                for (TypeVariable variable : declareClass.getSuperclass().getTypeParameters()) {
                    if (variable == typeVariable) {
                        index = internalIndex;
                        break;
                    }
                    internalIndex++;
                }
                if (index != -1) {
                    return ((ParameterizedType) declareClass.getGenericSuperclass()).getActualTypeArguments()[index];
                }
            }
        }

        return type;
    }