If you launch the client without making any modifications, it will not work. The reason for this is because by default, the "Client.java" file will have a server already set. This was the server used during development, and is not on anymore.
Edit the "Client.java file" Locate the line at the bottom of the file that says "Socket socket = new Socket("localhost", 1234);" Change the text that says "localhost" to the server IP of the chat server you wanna join, aswell as the port. Don't forget to save using CTRL + S (or file and then save)
JDK - https://download.oracle.com/java/22/latest/jdk-22_windows-x64_bin.msi JRE - https://www.java.com/en/download/manual.jsp
Now your done! just open the "launchclient.bat" file to automatically run the Client.java file and have fun chatting!