无法通过Facebook sdk 4.0获取当前用户个人资料

Question

我已将旧版本的Facebook sdk更改为新版本4.x并通过登录管理器成功集成了登录

     LoginManager.getInstance().registerCallback(callbackManager,
                        new FacebookCallback<LoginResult>() {
                            @Override
                            public void onSuccess(LoginResult loginResult) {
                                // App code
                                Profile profile = Profile.getCurrentProfile();
                                fb_first_name = profile.getFirstName();
                                fb_last_name = profile.getLastName();
                                facebookId = profile.getId();
                                Log.print("System out", "fb_first_name-------------> "+fb_first_name+"\fb_last_name-------------> "+fb_last_name+"fbID-------------> "+facebookId);

                            }

                            @Override
                            public void onCancel() {
                                 // App code
                                Toast.makeText(getApplicationContext(), "onCancel ", Toast.LENGTH_LONG).show();
                            }

                            @Override
                            public void onError(FacebookException exception) {
                                 // App code   
                                Toast.makeText(getApplicationContext(), "onError" +exception.toString() , Toast.LENGTH_LONG).show();
                            }
                });

但是当我从一个用户logout和另一个用户login时，配置文件显示的是旧用户。     如何获取新用户的个人资料？ 我也试过下面的代码来获取更新的个人资料。

profileTracker = new ProfileTracker() {
                @Override
                protected void onCurrentProfileChanged(
                        Profile oldProfile,
                        Profile currentProfile) {
                    // App code
                    fb_first_name = currentProfile.getFirstName();
                    fb_last_name = currentProfile.getLastName();
                    facebookId = currentProfile.getId();
                    Log.print("System out", "fb_first_name-------------> "+fb_first_name+"\fb_last_name-------------> "+fb_last_name+"fbID-------------> "+facebookId);


                    Toast.makeText(getApplicationContext(), "onSuccess"+currentProfile.getName(), Toast.LENGTH_LONG).show();
                    handler.sendEmptyMessage(0);
                }
            };