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import java.net.*;
import java.io.*;
 
public class chatserver
{
public static void main(String args[]) throws Exception
{
ServerSocket ss=new ServerSocket(2000);
Socket sk=ss.accept();
BufferedReader cin=newBufferedReader(newInputStreamReader(sk.getInputStream()));
PrintStream cout=new PrintStream(sk.getOutputStream());
BufferedReader stdin=new BufferedReader(new InputStreamReader(System.in));
String s;
while ( true )
{
s=cin.readLine();
if (s.equalsIgnoreCase("END"))
{
cout.println("BYE");
break;
}
System. out.print("Client : "+s+"\n");
System.out.print("Server : ");
s=stdin.readLine();
cout.println(s);
}
ss.close();
sk.close();
cin.close();
cout.close();
stdin.close();
}
}
 
public class chatclient
{
public static void main(String args[]) throws [...]

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import java.net.*;
import java.io.*;
public class server
{
public static void main(String args[]) throws Exception
{
ServerSocket ss=new ServerSocket(2000);
Socket s=ss.accept();
BufferedReader br=new BufferedReader(newInputStreamReader(s.getInputStream()));
double rad,area;
String result;
rad=Double.parseDouble(br.readLine());
System.out.println("From Client : "+rad);
area=Math.PI*rad*rad;
result="Area is "+area;
PrintStream ps=new PrintStream(s.getOutputStream());
ps.println(result);
br.close();
ps.close();
s.close();
ss.close();
}
}
public class client
{
public static void main(String args[]) throws Exception
{
 
Socket s=new Socket("192.168.0.19",2000);
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
String rad;
System.out.println("Enter radius of the circle ");
rad=br.readLine();
PrintStream ps=new PrintStream(s.getOutputStream());
ps.println(rad);
BufferedReader fs=newBufferedReader(new InputStreamReader(s.getInputStream()));
String result=fs.readLine();
System.out.println("From Server : "+result);
br.close();
fs.close();
ps.close();
s.close();
}
}

Output:
Java client
Enter [...]

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import java.awt.*;
import java.awt.event.*;
import java.applet.*;
/*
<applet code="Key" width=300 height=400>
</applet>
*/
public class Key extends Applet
implements KeyListener
{
int X=20,Y=30;
String msg="KeyEvents—>";
public void init()
{
addKeyListener(this);
requestFocus();
setBackground(Color.green);
setForeground(Color.blue);
}
public void keyPressed(KeyEvent k)
{
showStatus("KeyDown");
int key=k.getKeyCode();
switch(key)
{
case KeyEvent.VK_UP:
showStatus("Move to Up");
break;
case KeyEvent.VK_DOWN:
showStatus("Move to Down");
break;
case KeyEvent.VK_LEFT:
showStatus("Move to Left");
break;
case KeyEvent.VK_RIGHT:
showStatus("Move to Right");
break;
}
repaint();
}
public void keyReleased(KeyEvent k)
{
showStatus("Key Up");
}
public void keyTyped(KeyEvent k)
{
msg+=k.getKeyChar();
repaint();
}
public void paint(Graphics g)
{
g.drawString(msg,X,Y);
}
}

Output:

Java Keyboard programe output