Running into an java.net.BindException: Address al

Question

I am Running into a java.net.BindException: Address already in use (Bind failed) on a server-client socket app

I am trying to learn about Java sockets using a Youtube tutorial as a reference. My code seems to match everything in the video (except variables names) but, when trying to run the server and then the client sockets, I get:

Exception in thread "main" java.net.BindException: Address already in use (Bind failed)

I have tried even printing out the local port just to make sure I connect to the right available port but, nothing works. Is there any documentation I can look into to solve this problem? or any guidance?

Server.java

public class serverSocket {
 public static void main(String args[]) throws IOException{

  String message, serverResponse;

  ServerSocket serverSocket =  new ServerSocket(56789);
  System.out.print(serverSocket.getLocalPort());
  Socket acceptClientRequestSocket = serverSocket.accept();
  Scanner serverScanner = new Scanner(acceptClientRequestSocket.getInputStream());
  message = serverScanner.next();
   System.out.println(message);
  serverResponse = message.toUpperCase();

  PrintStream newMessage = new PrintStream(acceptClientRequestSocket.getOutputStream());
  newMessage.println(serverResponse);    

 }
}

Client.java

public class clientSocket {

public static void main(String args[]) throws UnknownHostException, IOException {

    String message,outputMessage;
    Scanner clientInput =  new Scanner(System.in);
    Socket clientSocket = new Socket("localhost",56789);
    Scanner incomingStream = new Scanner(clientSocket.getInputStream());
    System.out.println("Enter a message");
    message = clientInput.next();
    PrintStream printClientStream=  new PrintStream(clientSocket.getOutputStream());
    printClientStream.println(message);
    outputMessage = incomingStream.next();
    System.out.println(outputMessage);

}
}

Is there any documentation I can look into to solve this problem? or any guidance?

Answer 1

You have probably your previously exectued program still running. Check the running java processes. Kill the the previous one and try again.

If this wouldn't help try restarting your machine. If the problem persists after that then some service is already running on this port and is starting with the OS. In that case you can either change the port number in your app or disable that service.