I have over the past 5 days tried to find out why my program does not work i have been asking countless questions in here with good responses and it seems that i have now found the problem.
Background story:
I have a chat program that is devided into two seperate applications a Client and Server. The idea is to make a chat program so ever client has a GUI that contains a picture and some labels and a few textAreas.
Whenever the client starts up the Gui show and the user is able to hit the button connect to try and connect with the server the follwing this is directly what happens in my program and this part of the program works fine:
** The connect button is being pushed**
Client sends to server: 1
Server sends to client: 1
Server sends to client: 1
Client sends to server: Marc (The chat persons username)
Client sends to server: 5
Server sends to client: 1
server sends to client: 1
Server sends to client: Marc
Client sends to server: 8
Server sends to client: 8
And now all hell breaks loose because now the Thread in my Gui Starts. and from here on the program is apprently unable to recive messages from the server from here on. even though the server recives the messages. How can this be?
in order to not post loads of code i am going to post the important parts of my program if you need more code il be glad to update the post
the Thread (in the simpleController (the one that controls the GUI))
public void run(){
System.out.println("Thread started");
System.out.println(client.getSocket().isConnected());
ClientListner cl = new ClientListner(client);
while (client.getSocket().isConnected()) {
int key = 10;
if (client.getInput().hasNext()) {
txt_ChatPerson2.setText(client.reciveString());
txt_ChatPerson2.setVisible(true);
}
try {
key = client.reciveCommando();
System.out.println("jeg er her");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("Key "+key);
switch (key) {
// case 2 er recive chat:
case 2:
// først find ud af hvilket ID der har sendt chatten:
int y = 0;
try {
y = client.reciveCommando();
System.out.println("y" + y);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// derefter få beskeden og send den så ud til resten.
String says = client.reciveChat().toString();
System.out.println("Says :"+says);
if (y == 1) {
txt_ChatPerson1.setText(says);
txt_ChatPerson1.setVisible(true);
}else if (y == 2) {
txt_ChatPerson2.setText(says);
txt_ChatPerson2.setVisible(true);
}else {
chatPerson3.setVisible(true);
txt_ChatPerson3.setVisible(true);
txt_ChatPerson3.setText(says);
}
break;
default:
break;
}
}
}
The client class
import java.io.IOException;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import java.util.Scanner;
public class Client {
// disse var static
public final static int portNumber = 6040;
public Socket socket;
private PrintWriter pw;
private Scanner input;
private int clientId;
/**
* @param args
* @throws IOException
*/
public Client(Socket socket, PrintWriter pw, Scanner input, int clientId){
this.socket = socket;
this.pw = pw;
this.input = input;
this.clientId = clientId;
}
public void connect() throws IOException{
// du kan vælge at bruge inetadressen til at connecte i socketet.
InetAddress adr = InetAddress.getByName("localhost");
socket = new Socket("localhost", portNumber);
input=new Scanner(socket.getInputStream());
pw = new PrintWriter(socket.getOutputStream());
}
/**
* This method sends the message (that the client(chat person) writes to the user)
* @param x
* @throws NullPointerException
* @throws IOException
*/
public void SendChat(String x) throws NullPointerException{
pw.print("CHAT:"+x);
pw.flush();
/* pw.println(2);
pw.flush();
pw.println(SimpleController.currentClientId);
pw.flush();
pw.println(x);
pw.flush();
*/
}
public int sendCommando(int id) throws IOException{
System.out.println("Jeg sender"+ id);
pw.println(id);
pw.flush();
/*
* this part of the program sends a command to the server if the command is 1 then 1 is = Connect.
* the program then ask the server is the server is full or is it ok to connect?
* if the response is not 10 then the program will allow a connection to happen the return type will be the Id of which
* the chat person becomes!
*/
// should the method return 0 the Application will do NOTHING!
switch (id) {
case 1:
int k = reciveCommando();
if (k== 10) {
return 10;
}else if (k < 3) {
System.out.println("returned k" + k);
return k;
}else {
return 10;
}
/*
* Closes the connection with the server!
*/
case 3:
socket.close();
return 0;
case 5:
int y = reciveCommando();
return y;
case 8:
return 8;
default:
return 0;
}
}
/*
* this method recives a command from the server! the comands can be found in the ChatCommands.txt
* returns the command as an integer!
*/
public int reciveCommando() throws IOException{
Integer i = input.nextInt();
return i;
}
/**
* Gets a String response from the server. This method i used to create other users and give them the correct username.
*
* @param i
* @return
* @throws IOException
*/
public String getStringResponse(int i) throws IOException {
pw.print(i);
pw.flush();
String x = input.nextLine();
return x;
}
/*
* Work in progress - client getter og setter methoder!
*/
public Socket getSocket(){
return socket;
}
public Scanner getInput(){
return input;
}
public PrintWriter getPw(){
return pw;
}
public int getClientId(){
return clientId;
}
public void setClientId(int i ){
clientId = i;
}
public String reciveChat(){
return getInput().nextLine();
}
public String reciveString(){
String x =input.next();
return x;
}
public void sendString(String x){
pw.println(x);
pw.flush();
}
}
The server code
import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
public class Server extends Thread {
private Socket connection;
private PrintWriter pw;
private Scanner input;
private ServerInformation info = new ServerInformation();
private ChatPerson p;
public Server(Socket connection, PrintWriter pw, Scanner input){
this.connection = connection;
this.pw = pw;
this.input = input;
}
@Override
public void run() {
while (connection.isConnected()) {
if (input.hasNextInt()) {
System.out.println("Det var sgu da en int");
int i = getInput().nextInt();
System.out.println(i);
checkCommand(i);
}else if (input.hasNext()) {
System.out.println("det var ikke en int");
String inString = input.nextLine();
System.out.println(inString);
chatCase(inString);
}
}
}
private void chatCase(String x) {
String k =x.substring(6 , x.length());
System.out.println("k "+k);
pw.print(x);
pw.flush();
}
private void checkCommand(int i) {
System.out.println("i "+i);
switch (i) {
// this case accepts the connection and creates a new user;
case 1:
int id = info.getNextID();
pw.println(1);
pw.flush();
pw.println(id);
pw.flush();
p = new ChatPerson(id, input.next());
info.addToList(p);
break;
// this is the chat case virker ikke endnu
case 2:
int clientID = input.nextInt();
String x = reciveString();
System.out.println(x);
pw.println(clientID);
pw.flush();
pw.print(x);
pw.flush();
break;
// this case sends information about other chat users to the client
case 5:
pw.println(5);
pw.flush();
pw.println(info.getList().size());
pw.flush();
for (int j = 0; j < info.getList().size(); j++) {
pw.println(info.getList().get(j).getId());
System.out.println("info.get "+info.getList().get(j).getId());
pw.flush();
pw.println(info.getList().get(j).getName());
pw.flush();
}
break;
case 8:
pw.println(8);
pw.flush();
break;
default:
break;
}
}
private String reciveString() {
if (input.next().contains(" ")) {
String x = input.nextLine();
return x;
}
return input.next();
}
public Socket getConnection(){
return connection;
}
public PrintWriter getPw(){
return pw;
}
public Scanner getInput(){
return input;
}
}
i hope someone is able to help me since this is a huge problem for me if you need more info please just comment and il provide as much as possible
You have to rework your program.
GUI elements should be updated from within the GUI thread (EDT) only, not from a standalone thread.
Client connection should be divided in 2 weakly connected parts: sending messages and receiving them. Receiving should be a separate thread, and sending can be a thread or a class.
When the receiving thread have read a message, it sends it to EDT using
SwingUtilities.invokeLater(Runnable). Examples can be found elsewhere.When user have entered text, the text is send to the socket directly, or enqueued in a queue and later processed by the sending thread, if any.