[fovea1959]

Once you connect, you can call NetworkTableClient.getEntryStore().list() to get a list of all the existing key names in your client's copy of the table.

A listener will give you updated keys and values as they come in, so even if you don't get all the existing key names when you first connect, you'll be able to build a complete list of keys pretty quickly if you are sending them out in periodic().