すべてのクラスを取得する

public static void main(String args) {

  List interfaces = getAllClasses(HashMap.class);
  for (int i = 0; i < interfaces.size(); i++)

    System.out.println(interfaces.get(i));

}
public static List getAllClasses(Class clazz) {

  List classes = new ArrayList();

  return getAllClasses(clazz, classes);

}
public static List getAllClasses(Class clazz, List classes) {

  if(!classes.contains(clazz))

    classes.add(clazz);
  getAllInterfaces(clazz, classes);

  Class c = clazz.getSuperclass();
  if(c != null)

    getAllClasses(c, classes);
  return classes;

}
public static List getAllInterfaces(Class clazz, List classes) {

  Class interfaces = clazz.getInterfaces();
  for (int i = 0; i < interfaces.length; i++) {

    if(!classes.contains(interfaces[i]))

      classes.add(interfaces[i]);
    getAllInterfaces(interfaces[i], classes);

  }
  return classes;

}