Java Instant Messenger - Connecting multiple clients to server and oneanother -

i have written simple client/server instant messaging program, has basic functionality.

as stands, can send/receive messages between server , 1 connected client. however, subsequent clients not connect server.

i wish implement features allow following:

successful connection of 2+ clients server;

multiple clients connecting server , communicating each other , server.

i think need setup new thread each connection, i'm unsure how go this.

please advise (see code below).

any appreciated.

many thanks.

client.java:

import java.io.*; import java.net.*; import java.awt.*; import java.awt.event.*; import java.util.date; //timestamp functionality  import javax.swing.*;  public class client extends jframe { //inherits jframe      //1. creating instance variables      private jtextfield usertext; //where user inputs text     private jtextarea chatwindow; //where messages displayed     private string fulltimestamp = new java.text.simpledateformat("dd/mm/yyyy hh:mm:ss").format(new date());     //fulltimestamp - mm = months; mm = minutes; hh = 24-hour cloc     private objectoutputstream output; //output client server     private objectinputstream input; //messages received server     private string message ="";     private string serverip;     private socket connection;      //2. constructor (gui)     public client(string host){ //host=ip address of server         super("mick's instant messenger [client]");         serverip = host; //placed here allow access private string serverip         usertext = new jtextfield();         usertext.seteditable(false);         usertext.addactionlistener(             new actionlistener(){                 public void actionperformed(actionevent event){                     sendmessage(event.getactioncommand()); //for work, must build senddata method                     usertext.settext(""); //resets usertext blank, after message has been sent allow new message(s)                 }             }                  );         add(usertext, borderlayout.south);         chatwindow = new jtextarea();         add(new jscrollpane(chatwindow), borderlayout.center); //allows scroll , down when text outgrows chatwindow         chatwindow.setlinewrap(true); //wraps lines when outgrow panel width         chatwindow.setwrapstyleword(true); //ensures above line wrap occurs @ word end         setsize(400,320);         this.setlocationrelativeto(null); //places frame in center of screen         setvisible(true);     }      //3. startrunning method     public void startrunning(){         try{             connecttoserver(); //unlike server, no need wait connections. connects 1 specific server.             setupstreams();             whilechatting();         }catch(eofexception eofexception){               //display timestamp disconnection             showmessage("\n\n" + fulltimestamp);             showmessage("\nconnection terminated client! ");           }catch(ioexception ioexception){             ioexception.printstacktrace();         }finally{                 closecrap();             }      }      //4. connect server     void connecttoserver() throws ioexception{         showmessage(" \n attempting connection server... \n");         connection = new socket(inetaddress.getbyname(serverip), 6789);//server ip can added later         showmessage(" connected to: " +connection.getinetaddress().gethostname() ); //displays ip address of server     }      //5. setup streams send , receive messages     private void setupstreams() throws ioexception{          output = new objectoutputstream(connection.getoutputstream());         output.flush();         input = new objectinputstream(connection.getinputstream());         showmessage("\n streams setup! \n");      }      //6. while chatting method     private void whilechatting() throws ioexception{           //display timestamp connection         showmessage("\n" + fulltimestamp);          abletotype(true);         string timestamp = new java.text.simpledateformat("hh:mm:ss").format(new date());//timestamp         do{             try{                 message = (string) input.readobject(); //read input, treat string, store in message variable                 showmessage("\n" + message);             }catch(classnotfoundexception classnotfoundexception){                 showmessage("\n don't know object type");             }          //***broken timestamp?***             }while(!message.equalsignorecase("server " + "[" + timestamp  + "]" + ": " + "end")); //conversation happens until server inputs 'end'      }      //7. close streams , sockets     private void closecrap(){         showmessage("\n\nclosing streams , sockets...");         abletotype(false);//disable typing feature when closing streams , sockets         try{             output.close();             input.close();             connection.close();         }catch(ioexception ioexception){             ioexception.printstacktrace(); //show error messages or exceptions         }     }      //8. send messages server     private void sendmessage(string message){         try{         string timestamp = new java.text.simpledateformat("hh:mm:ss").format(new date());//timestamp         output.writeobject("client" + " [" + timestamp + "]" + ": " + message);         output.flush();         showmessage("\nclient" + " [" + timestamp + "]" + ": " + message);     }catch(ioexception ioexception){         chatwindow.append("\n error: message not sent!");     }      }      //9.change/update chatwindow     private void showmessage(final string m){         swingutilities.invokelater(                 new runnable(){                     public void run(){                         chatwindow.seteditable(false); //disallows text editing in chatwindow                         chatwindow.append(m); //appends text, passed in above                     }                 }                  );     }      //10. lets user type             private void abletotype(final boolean tof){                 swingutilities.invokelater(                         new runnable(){                             public void run(){                                 usertext.seteditable(tof); //passes in 'true' }         }                          );             } } 

server.java:

import java.io.*; import java.net.*; import java.awt.*; import java.awt.event.*;  import javax.swing.*;  import java.util.date;//timestamp functionality   public class server extends jframe{ //inherits jframe      //1. instance variables      private jtextfield usertext; //where messages typed     private jtextarea chatwindow; //where messages displayed     private string fulltimestamp = new java.text.simpledateformat("dd/mm/yyyy hh:mm:ss").format(new date());     //fulltimestamp - mm = months; mm = minutes; hh = 24-hour clock      //setting streams     private objectoutputstream output; //messages being sent user     private objectinputstream input; //messages being received user;      private serversocket server;      private socket connection; //socket = sets connection between 1 computer , another.      //2. constructor (gui)     public server(){     super("mick's instant messenger [server]"); //window title     usertext = new jtextfield();     usertext.seteditable(false); //you cannot type anything, unless connected else     usertext.addactionlistener(          new actionlistener(){         public void actionperformed(actionevent event){             sendmessage(event.getactioncommand());             usertext.settext(""); //resets editable text field after send message         }         }     );     add(usertext, borderlayout.south);//places user text input (jtextarea) field @ bottom     chatwindow = new jtextarea(15,30); //displays conversation     add(new jscrollpane(chatwindow));     chatwindow.setlinewrap(true); //wraps lines when outgrow panel width     chatwindow.setwrapstyleword(true); //ensures above line wrap occurs @ word end     setsize(400,320);     this.setlocationrelativeto(null); //places frame in center of screen     setvisible(true); //set visible on screen     }      //3.setup , run server     public void startrunning(){         try{             server = new serversocket(6789, 100);             //client connects @ port # 6789             //100 = queuelength - backlog of clients can wait @ port #6789 connect server              //while(true) ... means while loop going run forever             while(true){                 try{                     waitforconnection();                     setupstreams();                     whilechatting(); //allows messages pass , forth through streams                 }catch(eofexception eofexception){                      //connect , have conversation                     //display timestamp disconnection                     showmessage("\n\n" + fulltimestamp);                     showmessage("\nconnection terminated server! "); //displays end of stream/connection                   }finally{                     closecrap();                 }             }         }catch(ioexception ioexception){             ioexception.printstacktrace(); //displays info there's error!     }     }          //4. wait connection method, display connection info         private void waitforconnection() throws ioexception{             showmessage("\n server : waiting user(s) connect... \n "); //tells user server waiting connection             connection = server.accept();             //socket "connection" accept connections. creates socket each new connection.             showmessage("connected " +connection.getinetaddress().gethostname()); //displays ip address , hostname          }          //5. setup streams method.. streams send , receive data         private void setupstreams() throws ioexception{             output = new objectoutputstream(connection.getoutputstream());             //creates pathway allow connection whichever computer 'connnection' socket created.             output.flush(); //clears data gets left on in buffer when try connect else. flushes on other person.             input = new objectinputstream(connection.getinputstream());             //no flush here, because cannot flush else's stream             showmessage("\n streams setup! \n");          }          //6. during conversation method          private void whilechatting() throws ioexception{              //display timestamp connection             showmessage("\n" + fulltimestamp);              string message = "you connected! \n ";             sendmessage(message);             abletotype(true); //will allow user type text box after connection             string timestamp = new java.text.simpledateformat("hh:mm:ss").format(new date());//timestamp              do{                 try{                     message = (string) input.readobject(); //read incoming message string , store in 'message' variable.                     showmessage("\n" + message);//displays each message receive on new line                 }catch(classnotfoundexception classnotfoundexception){                     showmessage("/n don't know object user has sent!");                 }              //***broken timestamp?***                 }while(!message.equalsignorecase("client " + "[" + timestamp  + "]" + ": " + "end")); //allows conversation until client enters "end"          }          //7. close crap method - close streams , sockets after finished chatting         private void closecrap(){             showmessage("\n\n closing connections... \n");             abletotype(false);             try{                 output.close(); //close stream other users                 input.close(); //close incoming streams                 connection.close(); //close socket              }catch(ioexception ioexception){                 ioexception.printstacktrace();             } }         //8. send message method - send message client         private void sendmessage(string message){             try{                  //writeobject method built java.                  string timestamp = new java.text.simpledateformat("hh:mm:ss").format(new date());//timestamp                 output.writeobject("server" + " [" + timestamp + "]" + ": " + message);                 showmessage("\nserver" + " [" + timestamp + "]" + ": " + message); //shows ouput message in our conversation window                 output.flush();             }catch(ioexception ioexception){                 chatwindow.append("error: unable send message!");             }         }          //9. updates chatwindow - instead of creating entirely new gui each time         private void showmessage(final string text){         swingutilities.invokelater(                 new runnable(){                     public void run(){                         chatwindow.seteditable(false); //disallows text editing in chatwindow                         chatwindow.append(text); //appends text, passed in above                     }                 }                 );   }         //10. lets user type         private void abletotype(final boolean tof){             swingutilities.invokelater(                     new runnable(){                         public void run(){                             usertext.seteditable(tof); //passes in 'true'                         }                     }                     );            } } 

the way serversockets work in java clients want connect queued until can serversocket.accept() dequeues first 1 , returns it. therefore, multiple clients connected single server, need call accept multiple times. accept block until client available, may know.

you need create connection handler thread handles single client connection, , spawn threads off whenever new client connected. basically

while(true){     socket s=server.accept();     new connectionhandlerthread(s).start();     // write connectionhandlerthread } 

i write more detailed code you, i'm on mobile sorry.