首先你设置了user_birthday的权限吗?如果您想访问 user_birthday 信息，这一点非常重要

First of all have you set permission for user_birthday? it's very important if you want to access user_birthday information

如果用户不为空，通常你可以通过 user.getBirthday() 获取生日因为据我所知，您正在使用新的 facebook SDK

if the user is not null usually you can get the birthday by user.getBirthday() because from what I see you're using the new facebook SDK

您可以设置权限，例如当您使用 facebook authbutton 时

you can set permission for example when you using the facebook authbutton

authButton.setReadPermissions(Arrays.asList("user_location", "user_birthday", "user_likes"));

或者你可以重新授权

Session.ReauthorizeRequest reauthRequest = new Session.ReauthorizeRequest(this, PERMISSIONS).
                    setRequestCode(REAUTHORIZE_ACTIVITY).
                    setLoginBehavior(SessionLoginBehavior.SSO_WITH_FALLBACK);
session.reauthorizeForPublish(reauthRequest);

PERMISSION 是一个包含您的权限的数组

Where The PERMISSION is an array containing your permission