Java Programs[Important]

1. WRITE A JAVA PROGRAM that implements a simple client/server application. The client sends data to a server. The server receives the data, uses it to produce a result and then sends the result back to the client. The client displays the result on the console. For ex: The data sent from the client is the radius of a circle and the result produced by the server is the area of the circle.
2.  
3. Program :
4.  
5. // Server Program import   .io.*; 
6. import   .net.*; import   .util.*;
7.  
8. public class Server 
9. { 
10. public void static main (String args [ ] )
11.  { 
12. try 
13. { 
14. // create a server socket ServerSocket s = new ServerSocket(8000);
15.  
16. // start listening for connections on srver socket
17. 
    
18. Socket connectToClient = s.accept();
19.  
20. // create a buffered reader stream to get data from client BufferedReader isFromClient = new BufferedReader(new InputStreamReader (connectToClient.getInputStream()));
21.  
22. // create a buffer reader to send result to client PrintWriter osToClient = new PrintWriter(connectToClient.getOutputStream(), true);
23.  
24. // continuously read from client, process, send back while (true) { // read a line and create string tokenizer StringTokenizer st = new StringTokenizer(isFromClient.readLine());
25.  
26. //convert string to double double radius = new Double(st.nextToken()).doubleValue();
27.  
28. System.out.println(“Radius received from client: “ + radius);
29.  
30. // comput area double area = radius * radius *Math.PI;
31.  
32. // send result to client osToClient.println(area);
33.  
34. // print result on console System.out.println(“Area found: “ +area); }
35.  }
36.  catch (IOException e)
37.  { 
38. System.err.println(e); 
39. }
40.  } 
41. }
42. 
    
43. 
    
44. 
    
45. 
    
46. 
    
47. 
    
48. // Client Program import   .io.*;
49. 
    
50. import   .net.*; import   .util.*;
51.  
52. public class Client
53.  { 
54. public void static main (String args [ ] )
55.  {
56.  try
57.  { 
58. // create a socket to connect to server Socket connectToServer = new Socket(“local host”, 8000);
59.  
60. // create a buffered input stream to get result from server BufferedReader isFromServer = new BufferedReader(new InputStreamReader (connectToServer.getInputStream()));
61.  
62. // create a buffer output stream to send data to server PrintWriter osToServer = new PrintWriter(connectToClient.getOutputStream(), true);
63.  
64. // continuously send radius and get area
65.  while (true)
66.  { 
67. Scanner input=new Scanner(System.in);   
68. 
    
69. System.out.print(“Please enter a radius: “);
70.  double radius =input.nextDouble();
71.  
72. // display radius on console osToServer.println(radius);
73.  
74. // get area from server StringTokenizer st = new StringTokenizer(isFromServer.readLine());
75.  
76. // convert string to double Double area = new Double(st.nextToken()).doubleValue();
77.  
78. // print result on console System.out.println(“Area received from the server is: “ +area); 
79. }
80.  }
81.  catch (IOException e)
82.  { 
83. System.err.println(e); 
84. } 
85. } 
86. }