java - Implementation of a simple file transfer client server -

hi have following code client - server through thread, have errors,

can't setup server on port number.

can't setup server on port number.

but why?

class client:

import java.io.*; import java.net.socket;  // create class client public class client extends thread {  socket socket = null; socket socket1 = null;  // create send method  public  void sendfile() throws ioexception {  string host = "127.0.0.1"; string host1 = "127.0.0.2";  socket = new socket(host, 4444); socket1 = new socket(host1, 444);  file file = new file("/home/reza/desktop/link help"); file file1 = new file("/home/reza/desktop/hi"); long length = file.length(); long length1 = file1.length(); byte[] bytes = new byte[(int) length]; byte[] bytes1 = new byte[(int) length1];  fileinputstream fis = new fileinputstream(file); fileinputstream fis1 = new fileinputstream(file1);  bufferedinputstream bis = new bufferedinputstream(fis); bufferedoutputstream out = new bufferedoutputstream(socket.getoutputstream()); bufferedinputstream bis1 = new bufferedinputstream(fis1); bufferedoutputstream out1 = new bufferedoutputstream(socket1.getoutputstream());  int count; int count1;     while ((count = bis.read(bytes)) > 0) {     out.write(bytes, 0, count);  }  while ((count1 = bis1.read(bytes1)) > 0) {     out1.write(bytes1, 0, count1);  }    thread t = new thread(new runnable() {     public void run()  {   while(socket.isconnected())   {   wait2();      try {  sendfile();  } catch (ioexception e) {  e.printstacktrace();  }  }  }  });   thread t1 = new thread(new  runnable() {  public void run() {  while(socket1.isconnected())     {       wait2();          try {     sendfile();     } catch (ioexception e) {      e.printstacktrace();     }     }     }   });   t.start();   t1.start();   fis.close();  fis1.close();   out.close();  bis.close();  out1.close();  bis1.close();  socket.close();  socket1.close();  }    public void wait2()   {     try {    thread.currentthread().sleep(3000);     } catch (interruptedexception x) {    system.out.println("interrupted!");     }     }   } 

// class server

  import java.io.*;   import java.net.*;   public class server {     public  void recivefile() throws ioexception { serversocket serversocket = null; serversocket serversocket1 = null;   try {     serversocket = new serversocket(4444);    //serversocket1 = new serversocket(444);  } catch (ioexception ex) {     system.out.println("can't setup server on port number. "); } try {      serversocket1 = new serversocket(444);      } catch (ioexception ex) {         system.out.println("can't setup server on port number. ");     }   socket socket = null; socket socket1 = null;  inputstream = null; inputstream is1 = null;  fileoutputstream fos = null; fileoutputstream fos1 = null;  bufferedoutputstream bos = null; bufferedoutputstream bos1 = null;  int buffersize = 0; int buffersize1 = 0;   try {     socket = serversocket.accept();    socket1 = serversocket1.accept();     } catch (ioexception ex) {     system.out.println("can't accept client connection. "); }  try {     = socket.getinputstream();     is1 = socket1.getinputstream();       buffersize = socket.getreceivebuffersize();     buffersize1 = socket1.getreceivebuffersize();      system.out.println("buffer size: " + buffersize);     system.out.println("file recieved");     system.out.println("buffer size1: " + buffersize1);     system.out.println("file recieved");      system.out.println("file recieved"); } catch (ioexception ex) {     system.out.println("can't socket input stream. "); }   try {     fos = new fileoutputstream("/home/reza/desktop/reza");     bos = new bufferedoutputstream(fos);     fos1 = new fileoutputstream("/home/reza/desktop/ali");     bos1 = new bufferedoutputstream(fos1);    } catch (filenotfoundexception ex) {     system.out.println("file not found. "); }  byte[] bytes = new byte[buffersize];  int count;  while ((count = is.read(bytes)) > 0) {    bos.write(bytes, 0, count);  } byte[] bytes1 = new byte[buffersize1];  int count1; while ((count1 = is1.read(bytes1)) > 0) {        bos1.write(bytes1, 0, count1);     }   bos.flush(); bos.close(); bos1.flush(); bos1.close(); is.close(); is1.close(); socket.close(); serversocket.close(); socket1.close(); serversocket1.close();  }  public static void main(string[] args)  throws ioexception  { system.out.println("server run, please send file");    server s = new server(); s.recivefile();   } } 

error : can't setup server on port number. can't setup server on port number.

you can't start server on 127.0.0.2 - therein lies problem.