Programming Tutorials

Java Chat Client Sample Applet

By: Rajan in Java Tutorials on 2006-12-11  

Beginning in 2013, major web browsers began to phase out support for the underlying technology applets used to run, with applets becoming completely unable to be run by 2015–2017. Java applets were deprecated by Java 9 in 2017

You will probably be not able to test this code but if you just want to how an applet was used to write a Java Chat Client Application they you can check the below code. For thisChat client to work, you need to create a HTML file and embed this applet code inside.

First create the following HTML file and add this code inside the Body tag.

<script>

document.write('<applet code="chatclient.class" height=400
width=600>');

n=navigator.appVersion;

n=n.substring(0,n.indexOf(' '));

if (navigator.appName.indexOf("Microsoft")==0)

{ document.write("<param name='java11' value='0'>"); }

else

if (n<4.06) { document.write("<param name='java11'
value='0'>"); }

</script>

<param name="host" value="naken.inlink.com">

<param name="port" value="6666">

<param name="channel1" value="Linux Talk">

<param name="channel2" value="FreeBSD">

<param name="channel3" value="Windows Room">

<param name="font" value="MonoSpaced">

<param name="fontsize" value="13">

Java Chat Client Sample Code

import java.awt.*;
import java.applet.*;
import java.net.*;
import java.lang.*;
import java.io.*;

public class chatclient extends Applet implements Runnable
{
Scrollbar vertScroll;
DisplayArea myDisplay;
Thread myThread;
Socket mySocket;
InputStream myInputStream;
BufferedInputStream myBuffInput;
OutputStream myOutputStream;
Graphics gg;
TextField messageText,channelText,nameText;
Button LogButt;
int Online=0;
Checkbox echoBox,beepsBox,yellsBox;
Choice bgChoice,chanChoice,fontsizeChoice,fontChoice;
String YourName="";
int java11=1;

  public void init()
  {
  Panel NorthPanel=new Panel();
  Panel SouthPanel=new Panel();
  Panel EastPanel=new Panel();
  Panel CenterPanel=new Panel();
  int r=0;
  Label chanLabel;

    NorthPanel.setBackground(Color.lightGray);
    SouthPanel.setBackground(Color.lightGray);
    EastPanel.setBackground(Color.lightGray);
    CenterPanel.setBackground(Color.lightGray);

    setLayout(new BorderLayout());
    NorthPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

    SouthPanel.setLayout(new BorderLayout());
    SouthPanel.add("West",new Label("Message:"));
    SouthPanel.add("Center",messageText=new TextField());

    NorthPanel.add(chanLabel=new Label("Channel:",Label.RIGHT));
    NorthPanel.add(chanChoice=new Choice());
    NorthPanel.add(channelText=new TextField("Main",20));
    NorthPanel.add(new Label("Name:",Label.RIGHT));
    NorthPanel.add(nameText=new TextField("",15));

    chanChoice.addItem("---->");
    chanChoice.addItem("Main");
    chanChoice.addItem("Masquerade");
    r=1;
    while(getParameter("channel"+r)!=null)
    { chanChoice.addItem(getParameter("channel"+(r++))); }

    EastPanel.setLayout(new GridLayout(13,1));
    EastPanel.add(new Label("Background Color"));
    EastPanel.add(bgChoice=new Choice());
    EastPanel.add(new Label("Font"));
    EastPanel.add(fontChoice=new Choice());
    EastPanel.add(new Label("Font Size"));
    EastPanel.add(fontsizeChoice=new Choice());
    EastPanel.add(echoBox=new Checkbox("Private Echos",null,false));
    EastPanel.add(yellsBox=new Checkbox("Hush Yells",null,false));
    EastPanel.add(new Button("Who is On"));
    EastPanel.add(new Button("Finger"));
    EastPanel.add(new Button("List Channels"));
    EastPanel.add(new Button("Help"));
    EastPanel.add(LogButt=new Button("Logoff"));

    bgChoice.addItem("Black");
    bgChoice.addItem("White");

    fontChoice.addItem("Dialog");
    fontChoice.addItem("DialogInput");
    fontChoice.addItem("Helvetica");
    fontChoice.addItem("TimesRoman");
    fontChoice.addItem("Courier");
    fontChoice.addItem("Serif");
    fontChoice.addItem("SansSerif");
    fontChoice.addItem("Monospaced");

    for (r=6; r<20; r++) { fontsizeChoice.addItem(""+r); }

    CenterPanel.setLayout(new BorderLayout());
    CenterPanel.add("Center",myDisplay=new DisplayArea());
    CenterPanel.add("East",
          vertScroll=new Scrollbar(Scrollbar.VERTICAL,100,100,0,100));
    vertScroll.show();

    add("South",SouthPanel);
    add("North",NorthPanel);
    add("East",EastPanel);
    add("Center",CenterPanel);

    if (getParameter("fontsize")!=null)
    { myDisplay.fontsize=Integer.parseInt(getParameter("fontsize")); }
      else
    { myDisplay.fontsize=13; }

    if (getParameter("java11")!=null)
    { java11=Integer.parseInt(getParameter("java11")); }

    if (getParameter("font")!=null)
    { myDisplay.font=getParameter("font"); }
      else
    { myDisplay.font="Dialog"; }

    myDisplay.setup(vertScroll.size().width,java11);
    // System.out.println(java11);
    myDisplay.myBar=vertScroll;
    gg=myDisplay.getGraphics();
    fontsizeChoice.select(""+myDisplay.fontsize);
    fontChoice.select(myDisplay.font);
  }

  public void start()
  {
  int l;

    l=logon();
    if (l==0)
    { 
      myThread=new Thread(this);
      myThread.start();
    }
  }

  public int logon()
  {
    try 
    {
      mySocket=new Socket(getParameter("host"),Integer.parseInt(getParameter("port"))); 
      myInputStream=mySocket.getInputStream(); 
      myBuffInput=new BufferedInputStream(myInputStream,2048);
      myOutputStream=mySocket.getOutputStream(); 
      Online=1;
    }
    catch (Exception e) { Online=0; }

    if (Online==1) return 0;

    return 1;
  }

  public void run()
  {
  byte[] in=new byte[2048];
  int r,c=0;
  String myString="";

    if (Online==1)
    { 
      if (getParameter("YourName")!=null)
      {
        nameText.setText(getParameter("YourName"));
        try 
        { myOutputStream.write(convb(".n"+getParameter("YourName")+"\n")); }
        catch (Exception e) {}
        YourName=getParameter("YourName");
      }
    }

    while(true)
    {
      if (Online==1)
      {
        try { c=myBuffInput.read(in,0,2048); } catch (Exception e) { Online=0; }
        for(r=0; r> Private beeps are now on."); }
            else
          { myDisplay.AddText(">> Private beeps are now off."); }
        }
          else
        if (message.startsWith(".e"))
        { echoBox.setState(!echoBox.getState());  }
          else
        if (message.startsWith(".h"))
        {
          message="";
          myDisplay.AddText(">> This is automatic here.");
        }

        myOutputStream.write(convb(message+"\n"));
        messageText.setText("");
      }
        else
      if (e.target==nameText)
      { 
        if (!nameText.getText().equals(YourName))
          myOutputStream.write(convb(".n"+nameText.getText()+"\n"));
        YourName=nameText.getText();
      }
        else
      if (e.target==chanChoice)
      {
        if (chanChoice.getSelectedIndex()!=0)
        {
          myOutputStream.write(convb(".c"+chanChoice.getSelectedItem()+"\n")); 
          channelText.setText(chanChoice.getSelectedItem());
          chanChoice.select(0);
        }
      }
        else
      if (obj.equals("Who is On")) 
      { myOutputStream.write(convb(".w\n")); }
        else
      if (obj.equals("Finger"))
      { myOutputStream.write(convb(".f\n")); }
        else
      if (obj.equals("List Channels"))
      { myOutputStream.write(convb(".a\n")); }
        else
      if (obj.equals("Help"))
      { myOutputStream.write(convb(".he\n")); }
        else
      if (obj.equals("Logoff"))
      { 
        myOutputStream.write(convb(".q\n"));
        Online=0;
        LogButt.setLabel("Log On");
      }
        else
      if (obj.equals("Log On"))
      {
        logon();
        LogButt.setLabel("Logoff");
      }
        else
      if (e.target.toString().indexOf("Private Beeps")>=0)
      { 
        myDisplay.beeps=myDisplay.beeps^1;
        if (myDisplay.beeps==1)
        { myDisplay.AddText(">> Private beeps are now on."); }
          else
        { myDisplay.AddText(">> Private beeps are now off."); }
      }
        else
      if (e.target.toString().indexOf("Hush Yells")>=0)
      { myOutputStream.write(convb(".hu\n")); }
        else
      if (e.target.toString().indexOf("Private Echos")>=0)
      { myOutputStream.write(convb(".e\n")); }
        else
      if (e.target.toString().indexOf("Back To Main")>=0)
      {
        myOutputStream.write(convb(".c0\n"));
        channelText.setText("Main");
      }
        else
      if (e.target==fontsizeChoice)
      {
	myDisplay.fontsize=Integer.parseInt(fontsizeChoice.getSelectedItem());
	myDisplay.recalc();
        myDisplay.paint(gg);
      }
	else
      if (e.target==fontChoice)
      {
	myDisplay.font=fontChoice.getSelectedItem();
	myDisplay.recalc();
        myDisplay.paint(gg);
      }
        else
      if (obj.equals("Black"))
      { 
        myDisplay.fgColor=Color.white; 
        myDisplay.bgColor=Color.black;
        myDisplay.paint(gg);
      }
        else
      if (obj.equals("White"))
      { 
        myDisplay.fgColor=Color.black; 
        myDisplay.bgColor=Color.white;
        myDisplay.paint(gg);
      }
    }
    catch (Exception ex) {}
 
    return false;
  }

  byte[] convb(String myString)
  {
  byte[] myBytes=new byte[2048];
  int r;
   
    for(r=0; r0)
    {
      if (myString.charAt(0)=='>') sflag=1;
        else
      if (myString.charAt(0)=='<') 
      {
        sflag=2; 
        if (beeps!=0) System.out.println((char)7);
      }
        else
      if (myString.charAt(0)=='#') sflag=3;
        else
      if (myString.charAt(0)=='-') sflag=4;
    }
   
    while(myString.length()>0)
    {
      if (fm.stringWidth(myString)=0 && 
            fm.stringWidth(myString.substring(0,r))>d.width-scrollbarSize)
      { r--; }

      spc=0; last=0;

      while((spc=myString.indexOf(' ',spc+1))0) last=spc;
      if (last<=0) { last=r; }
      AddLine(myString.substring(0,last),sflag);
      myString=myString.substring(last,myString.length()).trim();
    }
  }

  public void AddLine(String myString,byte flags)
  {
    BFlags[topptr]=flags;
    Buffer[topptr++]=myString;
    if(topptr==max) topptr=0;

    ScrollRecalc(0);
  }

  public void ScrollRecalc(int i)
  {
  int scrollvis=max;
  int value=0;

/* recalculate scrollbar size */

/* max is maximum number of lines */
/* bsize the current number of text lines in buffer (including on screen) */
/* lastbsize the last bsize */
/* lines is the number of visible text lines on the screen */

/* here */

    if (bsizelines) 
      {
        scrollvis=bsize-lines;
        value=bsize-lines;
      }
        else
      { 
/* beginning state */
	scrollvis=1;
        value=1;
      }

      if (java11==1)
      { myBar.setValues(bsize,lines,0,bsize); }
	else
      { myBar.setValues(value,scrollvis*2,1,value); }

      scrollval=myBar.getValue(); 
    }
      else
    { 
      if (i==1)
      {
        value=bsize-lines;
        scrollvis=bsize-lines;
        if (java11==1)
        { myBar.setValues(bsize,lines,0,bsize); }
  	  else
        { myBar.setValues(value,scrollvis*2,1,value); }
      }
	else
      { myBar.setValue(bsize); }
    }
    
    scrollval=bsize; 
  }

  public void paint(Graphics ggReal)
  {
  Dimension d;
  int r,l;
  int ptr,offset;

    d=this.size();
    if (OffScreen==null)
    {
      OffScreen=createImage(d.width,d.height);
      gg=OffScreen.getGraphics();
    }
    
    gg.setColor(bgColor);
    gg.setFont(myFont);
    gg.fillRect(0,0,d.width,d.height);
    l=0;
    lines=d.height/spacing;
    if (bsize<=lines) { offset=0; }
      else
    { offset=(bsize-lines-myBar.getValue()); }
    myBar.setPageIncrement(lines);
    ptr=topptr-lines-offset;
    while (ptr<0) ptr=ptr+max;

    for (r=0; r0)
          {
            if (BFlags[ptr]==1) { gg.setColor(msColor); }
              else
            if (BFlags[ptr]==2) { gg.setColor(Color.blue); }
              else
            if (BFlags[ptr]==3) { gg.setColor(Color.red); }
              else
            { gg.setColor(fgColor); } 
          }
            else
          { gg.setColor(fgColor); } 
          l=l+spacing;
          gg.drawString(Buffer[ptr],3,l);
        }
        if (++ptr==max) ptr=0;
      }
    }
  ggReal.drawImage(OffScreen,0,0,null);

  }
}