I have a problem (obviously). I am noob in UDP in java sorry.
I am making an application for sending and receive UDP datagrams.The idea to run 2 times the same program and send and receive packets, which I am doing with threads. The problem , receibve this program always gives me the same message.
java.net.BindException: Address already in use
It has to do with the port that I try to open in use, but I do so with any port you try, 80, 8080, 12345. Even watch online command ports were free, but if you tell me who are equally busy.
netstat -a
The code is :
Sender
class envioNodo extends Thread {
byte[] tablaEnca = new byte[10000];
int port = 0;
int puertoVecino = 0;
String IP_envio = "" , IP_emisor ="";
public envioNodo(String tE , String IP , int puerto , String IP_e) {
port = puerto;
IP_envio = IP;
IP_emisor = IP_e;
System.out.println("Se enviará el vector de distancias a la IP "+ IP_envio +" con puerto "+ port);
}
public void run() {
System.out.println("Se ejecuta el envio de paquetes del nodo");
try {
DatagramSocket dS = new DatagramSocket(); // null //Sin null envia los datos por un puerto cualquiera udp
dS.setReuseAddress(true);
DatagramPacket dP = null;
try {
dP = new DatagramPacket(tablaEnca , tablaEnca.length, InetAddress.getByName(IP_envio) , port);
dS.send(dP);
System.out.println("Paquete enviado");
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e){
e.printStackTrace();
}
try {
dS.send(dP);
} catch (IOException e) {
e.printStackTrace();
}
dS.close();
} catch (SocketException e) {
e.printStackTrace();
}
}
}
Receive
class recepcionNodos extends Thread {
int port = 0;
String vD_rN ;
byte[] buff = new byte[10000];
DatagramPacket dP = null;
DatagramSocket dS = null;
public recepcionNodos(int puerto){
port = puerto;
System.out.println("Inicio del hilo de espera de respueta");
System.out.println("El puerto por el que se escuchara es el "+ port);
}
public void run(){
do{
try {
System.out.println("Comienzo recepcion");
port++;
dS = new DatagramSocket(port);
dP = new DatagramPacket(buff,buff.length);
System.out.println("Espera en el receive");
dS.receive(dP);
vD_rN = new String(dP.getData()).substring(0,dP.getLength());
System.out.println("String recibido.");
System.out.print(vD_rN);
System.out.println("Paquete recibido!");
} catch (IOException e) {
System.out.println("Error en recepcion del paquete!");
e.printStackTrace();
System.exit(1);
}
}while(true);
}
Whit DatagramSocket and DatagramPacket = null.
I Start whit send DatagramSocket = new DatagramSocket(); In this position the constructor get first port can send datagram , ¿But receive i dont know , How do can't receive the packets UDP?
Edit : i have 2 interfaces 10.0.0.1 10.0.0.2 and run one program en one interface whit :
Sudo ip addr add
Solution :
class recepcionNodos extends Thread {
int port = 0 , aux = 0;
String vD_rN ;
byte[] buff = new byte[10000];
DatagramPacket dP = null;
DatagramSocket dS = null;
public recepcionNodos(int puerto){
port = puerto;
System.out.println("Inicio del hilo de espera de respueta");
System.out.println("El puerto por el que se escuchara es el "+ port);
}
public void run(){
do{
try {
System.out.println("Comienzo recepcion");
port++;
dS = new DatagramSocket(port);
dP = new DatagramPacket(buff,buff.length);
System.out.println("Espera en el receive");
dS.receive(dP);
vD_rN = new String(dP.getData()).substring(0,dP.getLength());
System.out.println("String recibido.");
System.out.print(vD_rN);
System.out.println("Paquete recibido!");
} catch (IOException e) {
System.out.println("Error en recepcion del paquete!");
e.printStackTrace();
e.printStackTrace();
Rip r = new Rip();
port = Rip.generarPuerto(); // and this function
System.out.println(port);
if(aux != 0)
System.exit(1);
aux++;
}
}while(true);
}
This is :
public static int generarPuerto() {
int aux = 0;
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
Random r = new Random();
r.setSeed(r.nextLong());
aux = r.nextInt(49151 - 1024 - 1) + 1024;
return aux;
}
My problem is :
2 interfaces :
10.0.0.1
10.0.0.2
And run in a aplication whit 1 IP and other whit other IP , but i think the ports is independents . I use this function and no broblem , but now have the problem i can't receive mensage.
PD : And any whit very much experience or reputation wants to reform the post is free. PD2 : Sorry , very long post and very much edits. PD3 : Very much thx for help , this forum is the best for problems programming.
