JVM BIND ERROR using GDX NET api

Question

I am using this code to start a simple server using the libgdx net api (I am currently working with libgdx, so i will use this api in the future)

  Server server = new Server(1234);

The line calls this class:

package com.me.mygdxgame;

import java.io.BufferedReader;
import java.io.InputStreamReader;

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.Net;
import com.badlogic.gdx.net.ServerSocket;
import com.badlogic.gdx.net.Socket;

public class Server extends Thread {
    int port;
    ServerSocket server;
    boolean running = true;

    public Server(int port) {
    this.port = port;

    this.start();
    }

    @Override
    public void run() {
    Socket s = null;
    String text = "";
    try {
        server = Gdx.net.newServerSocket(Net.Protocol.TCP, port, null);
        s = server.accept(null);
        BufferedReader in = new BufferedReader(new InputStreamReader(
            s.getInputStream()));
        while (s.isConnected()) {
        text = in.readLine();
        if (text != "") {
            Gdx.app.log("Output", text);
            Gdx.app.exit();
        }
        }

        in.close();

    } catch (Exception e) {
        e.printStackTrace();
    }
    }
}

My problem is, that i am getting an JVM BIND error all the time. I am using port 1234. It is open in my routers configuration (I opened it), and unused netstat says. The Programm is whitelistet in my firewall, so I don't know where the problem is. Here is the error (it repeats infinite times, until I close the program (although there isn't any loop?)

com.badlogic.gdx.utils.GdxRuntimeException: Cannot create a server socket at port 1234.
    at com.badlogic.gdx.backends.lwjgl.LwjglServerSocket.<init>(LwjglServerSocket.java:68)
    at com.badlogic.gdx.backends.lwjgl.LwjglNet.newServerSocket(LwjglNet.java:44)
    at com.me.mygdxgame.Server.run(Server.java:27)
Caused by: java.net.BindException: Address already in use: JVM_Bind
    at java.net.DualStackPlainSocketImpl.bind0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketBind(Unknown Source)
    at java.net.AbstractPlainSocketImpl.bind(Unknown Source)
    at java.net.PlainSocketImpl.bind(Unknown Source)
    at java.net.ServerSocket.bind(Unknown Source)
    at java.net.ServerSocket.bind(Unknown Source)
    at com.badlogic.gdx.backends.lwjgl.LwjglServerSocket.<init>(LwjglServerSocket.java:64)
    ... 2 more

Answer 1

Port 1234 is already in use. Check netstat. Maybe an earlier instance of your program is still running, or maybe there are still ports in TIME-WAIT state.