//libraries are imported
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;


public class Server1
{
	public static void main(String[] args) throws Exception
	{
		//socket for server is created
		ServerSocket messageSocket1 = null, messageSocket2 = null;
		//Try to set IPv4 instead of 6 and initialize serverSocket to port 5555(this port can be changed if so desired)
		try
		{
			System.setProperty("java.net.preferIPv4Stack", "true");

			messageSocket1 = new ServerSocket(5555,1);
			messageSocket2 = new ServerSocket(5556,1);

		}
		//catch if couldn't initialize serverSocket on port 5555, tell user and quit program
		catch (IOException e)
		{
			System.out.println("Couldn't listen on port 5555/5556 Check port");
			System.exit(-1);
		}
		//create socket for client
		Socket inSocket1 = null;
		Socket inSocket2 = null;
		//infinite while loop keeps program running until told to quit
		while(true)
		{
			System.out.println("Looking for clients");
			//try to connect server socket to client socket
			try
			{
				inSocket1 = messageSocket1.accept();
				inSocket2 = messageSocket2.accept();
			}
			//catch if can't connect, tell user and quit program
			catch (IOException e)
			{
				System.out.println("didn't find client, check port/client program");
				System.exit(-1);
			}
			//in takes in the user input from the user
			System.out.println("Connection to clients made");
			BufferedReader in1 = new BufferedReader(new InputStreamReader(inSocket1.getInputStream()));
			BufferedReader in2 = new BufferedReader(new InputStreamReader(inSocket2.getInputStream()));
			//out sends user input to the client
			PrintWriter out1 = new PrintWriter(inSocket1.getOutputStream(),true);
			PrintWriter out2 = new PrintWriter(inSocket2.getOutputStream(),true);
			//String takes input from in
			String userInput1 = "";
			String userInput2 = "";
			//while user does not type "exit"
			while(true)
			{
				//userInput from client1
				if(userInput1.equals("Client 1: quit")||userInput2.equals("Client 2: quit"))
				{
					//close all sockets
					out1.close();
					in1.close();
					messageSocket1.close();
					inSocket1.close();
					out2.close();
					in2.close();
					messageSocket2.close();
					inSocket2.close();

					System.exit(0);
				}
				userInput1 = in1.readLine();
				//sned message to client2
				out2.println(userInput1);
				//userinput from client2
				userInput2 = in2.readLine();
				//send the message to the client1
				out1.println(userInput2);

			}


		}

	}
}





import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

public class Client1
{
	public static void main(String args[]) throws IOException
	{
		Socket messageSocket = null;
		PrintWriter out = null;
		BufferedReader in = null;

		try
		{
			//get program to use IPv4 instead of 6
			System.setProperty("java.net.preferIPv4Stack", "true");

			messageSocket = new Socket("localhost", 5555);
			out = new PrintWriter(messageSocket.getOutputStream(), true);
			in = new BufferedReader(new InputStreamReader(messageSocket.getInputStream()));

		}
		catch (IOException e)
		{
			System.out.println("can't open socket on 5555");
			System.exit(-1);
		}

		Scanner keyboard = new Scanner(System.in);

		System.out.println("Enter your message. type quit to exit");
		String message = ("Client 1: "+keyboard.nextLine());

		while(true)
		{
			if(message.contains("quit"))
			{
				System.exit(0);
			}

			out.println(message);
			System.out.println(in.readLine());
			System.out.print("you: ");
			message = ("Client 1: "+keyboard.next());

		}


	}
}





import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

public class Client2
{
	public static void main(String args[]) throws IOException
	{
		Socket messageSocket = null;
		PrintWriter out = null;
		BufferedReader in = null;

		try
		{
			//get program to use IPv4 instead of 6
			System.setProperty("java.net.preferIPv4Stack", "true");
			messageSocket = new Socket("localhost", 5556);
			out = new PrintWriter(messageSocket.getOutputStream(), true);
			in = new BufferedReader(new InputStreamReader(messageSocket.getInputStream()));

		}
		catch (IOException e)
		{
			System.out.println("can't open socket on 5555");
			System.exit(-1);
		}

		Scanner keyboard = new Scanner(System.in);

		String message = "";

		while(true)
		{
			if(message.contains("quit"))
			{
				System.exit(0);
			}

			System.out.println(in.readLine());
			System.out.print("you: ");
			message = ("Client 2: "+keyboard.nextLine());
			out.println(message);
		}



	}
}