It is one of many small java-projects, that I did on the basis of the spezialist java courses levels 1 and 2.
There are two projects in one repository here: client-side and server-side. First, the server application is launched, followed immediately by the client application. The client connects to the server and lets you send commands to the server. The server duplicates them on its side to the console, sends a response to the client. The close command terminates the connection at the initiative of the client.
Other related repositories: java_repeat, swing_box, swing_write_read, java_fx.