If you're used to using Toad, Sql developer interface is similar but a bit different. I'm guessing here, but you're probably Connecting as UserB, and expecting to see all schema objects under Connections. However, in Sql Developer, what is shown under Connections is only objects owned by that connected user, not all objects.
You want to use "Schema Browser" in Sql Developer. To do this, just right click onto the UserB connection and choose Schema Browser. You will then have a drop-down at the top left corner of the page to select the owner you wish (UserA in this case). The second drop-down under that is to select the type of object (table, function, procedure, package, etc...)
Hope that helps.