block2.java

getUserInfo(new CallBack() {
    @Override
    public void onSuccess(String user) {
        if (user != null) {
            System.out.println(user);
            getFriendList(user, new CallBack() {
                @Override
                public void onSuccess(String friendList) {
                    if (friendList != null) {
                        System.out.println(friendList);
                        getFeedList(friendList, new CallBack() {
                            @Override
                            public void onSuccess(String feed) {
                                if (feed != null) {
                                    System.out.println(feed);
                                }
                            }
                        });
                    }
                }
            });
        }
    }
});