Huge UPDATE: I added the possibility/feature to handle multiple connections! I am so proud of myself. 
If someone in the future is reading this, who wants to know how to handle multiple TCPSockets with ServerSockets, you can mention my name in your thread.
Keywords for search engine:
handling multiple tcpsockets with serversockets
how to get one connection from serversockets
one socket from serversocket
get tcpsocket from serversocket
get one socket from ActiveConnections
handle socket ActiveConnections
ServerSocket.ActiveConnections