I am trying to create a messenger program and have successfully set up client-server connections using sockets. However I am finding it difficult to code the process of having several clients communicating simultaneously. Shown in the code below is the methods for the chats that are held within a ClientThread class that regulates the interaction between client and server using threads stored in a shared ArrayList. How would you implement the code for multiple peer-to-peer chats here?
startChat method:
public void startChat()
{
// start the convo!
// first of all the user chooses who to speak to
// starts a loop until user enters a valid username or 'Group'
String line = "";
boolean validCommand = false;
while(validCommand == false)
{
try {
line = in.readLine();
} catch (IOException e) {
System.out.println("Problem reading reply about user chat");
}
if(line.equalsIgnoreCase("Group"))
{
validCommand = true;
chatAll(); // an integer of negative one starts a chat with everyone
}
else
{
synchronized(this){
// find user
for(int i = 0; i < threads.size(); i++)
{
if(threads.get(i) != null && threads.get(i).username != null)
{
if(threads.get(i).username.equals(line)) // means that we have found the index of the thread that the client wants to speak to
{
/*// START : BETWEEN THESE CAPITALISED COMMENTS IS MY ATTEMPT TO INITIATE TWO WAY CHAT
int thisIndex = -1;
for(int j = 0; j < threads.size(); j++) // gets the index of this thread object in the array
{
if(threads.get(j) == this)
{
thisIndex = j;
// out.println(j);
}
}
if(thisIndex != -1)
{
threads.get(i).out.println(username + " is trying to connect");
threads.get(i).processChat(thisIndex); // this is the line causing the problem!
}
// END : BETWEEN THESE CAPITALISED COMMENTS IS MY ATTEMPT TO INITIATE TWO WAY CHAT */
threads.get(i).out.println(username + " is trying to connect");
out.println("Chat with " + threads.get(i).username);
processChat(i);
validCommand = true;
}
// if the command is not group and not a username, it is not valid and we ask the user to re-enter
else if(i == threads.size() - 1)
{
out.println("This command is not valid, please re-enter");
}
}
}
} // end of synchronised bit
} // end of else statement
} // end of while loop
}
allChat method:
void chatAll()
//for the purpose of group chat
{
out.println("Group chat initiated");
boolean d = true;
while(d == true)
{
String message = "";
try {
message = in.readLine();
} catch (IOException e) {
System.out.println("Can't read line from client");
}
if(message.contains("goodbye") == true)
{
d = false;
}
else
{
synchronized(this)
{
for(int j = 0; j < threads.size(); j++)
{
if(threads.get(j) != null)
{
threads.get(j).out.println(username + ": " + message);
}
}
}
}
}
}
processChat method:
void processChat(int i)
//for the purpose of talking to pre-defined user
{
boolean d = true;
while(d == true)
{
String message = "";
try {
message = in.readLine();
} catch (IOException e) {
System.out.println("Can't read message from client");
}
if(message.contains("goodbye") == true)
{
d = false;
}
else {
if(threads.get(i) != null)
{
threads.get(i).out.println(username + ": " + message);
}
}
}
}
Just for good measure and a reference here is the overall client class (confusingly labelled ThreadedClient as opposed to ClientThread haha)
ThreadedClient class:
import java.net.*;
import java.io.*;
public class ThreadedClient implements Runnable {
// client socket
private static Socket clientSocket = null;
//I/O streams to and from the server
private static BufferedReader in = null;
private static PrintStream out = null;
// Input stream to read user input
private static BufferedReader inputReader = null;
private boolean open = true;
public ThreadedClient(String host, int port)
{
startConnection(host, port);
}
public void startConnection(String host, int port)
{
//open up the socket
try {
clientSocket = new Socket(host, port);
} catch (UnknownHostException e) {
System.out.println("The host name '" + host + "' isn't known");
} catch (IOException e) {
// TODO Auto-generated catch block
System.out.println("Cannot create socket");
}
// connect I/O streams
try {
in = new BufferedReader(new InputStreamReader(new DataInputStream(clientSocket.getInputStream())));
out = new PrintStream(clientSocket.getOutputStream());
inputReader = new BufferedReader(new InputStreamReader(System.in));
} catch (IOException e) {
System.out.println("Problem connecting streams");
}
// process the chat itself
// the thread deals with input coming in
Thread thread = new Thread(this);
thread.start();
// the loop deals with output
while(open == true)
{
String message;
try {
message = inputReader.readLine();
out.println(message);
if(message.contains("goodbye") == true)
{
open = false;
}
} catch (IOException e) {
System.out.println("Problem sending messages");
}
}
// chat is done, so we can close resources
try {
in.close();
inputReader.close();
out.close();
clientSocket.close();
} catch (IOException e) {
System.out.println("Problem closing resources");
}
}
// run method for sending input out. I imagine this will not be necessary in the GUI implemented version, as we can use
// an action listener for the send function, e.g. one that reads a text field into a output stream everytime the user clicks enter
public void run() {
while(open == true)
{
try {
String response = in.readLine();
if(response.contains("goodbye") == true)
{
open = false;
}
System.out.println(response);
} catch (IOException e) {
System.out.println("Problem recieving messages");
}
}
}
public static void main(String[] args)
{
ThreadedClient socket = new ThreadedClient("localhost", 50000);
}
}
I know that this code may not be as advanced as some others I have seen on this forum as well as DreamInCode and others but I was trying to build it from scratch and have been stuck here for what feels like a millennia. Trawling through the internet has not helped :(
Any suggestions and criticisms would be an absolute God send!
Thanks in advance guys.
https://stackoverflow.com/questions/22512424
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