CODEWITHSUNDEEP
javanetwork-programmingudpclient-server
water
water

Reputation: 535

UDPServer does not receive the sent data from the UDPClient

I have the following UDP client and servcer classes and I am trying to send some string from the UDPClient to the another class 'UDPServer' in the same java project at the localhost and port 7777. I am facing problem that I am not receiving anything in the UDPServer class from the UDPClient class. Does anyone have an idea where the problem is?

I appreciate any help!

UDPClient

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;


class UDPClient {

    public static void main(String args[]) throws Exception {
        String aString = "Hello World";
        DatagramSocket clientSocket = new DatagramSocket();
        InetAddress IPAddress = InetAddress.getByName("localhost");
        byte[] sendData = new byte[1024];
        byte[] receiveData = new byte[1024];
        sendData = aString.getBytes();
        DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 7777);
        clientSocket.send(sendPacket);
        DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
        clientSocket.receive(receivePacket);
        String modifiedSentence = new String(receivePacket.getData());
        System.out.println("FROM SERVER:" + modifiedSentence);
        clientSocket.close();
    }
}

UDPServer

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;


class UDPServer {

        public static void main(String args[]) throws Exception {
            DatagramSocket serverSocket = new DatagramSocket(7777);
            byte[] receiveData = new byte[1024];
            byte[] sendData = new byte[1024];
            while (true) {
                DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
                serverSocket.receive(receivePacket);
                String sentence = new String(receivePacket.getData());
                System.out.println("RECEIVED: " + sentence);
                InetAddress IPAddress = receivePacket.getAddress();
                int port = receivePacket.getPort();
                String capitalizedSentence = sentence.toUpperCase();
                sendData = capitalizedSentence.getBytes();
                DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, port);
                serverSocket.send(sendPacket);
            }
        }
}

Upvotes: 1

Views: 148

Answers (1)

Saulius Next
Saulius Next

Reputation: 1330

Hi try to check what wrong with port allocation, because you code works ok.

Start your server and run this command:

Windows

 netstat -aon | FINDSTR 7777

Linux:

 netstat -aon | grep 7777

You should see the PID check if pid is same as UDPServer runs on. Also check firewall maybe there is something wrong?

Upvotes: 1

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