title: Why does my TCP connection close after running a command? - Java
body: <p>I have a simple FTP server and client. For now, the client can send a file, and the server can accept it, but after i run a sendFile() command, it transfers the file, and the server and the client terminate, making it unable to run any other commands after that. </p>
  
  <p>SERVER   </p>
  
  <pre><code>import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.net.ServerSocket;
  import java.net.Socket;
  
  import mmd.filetransfer.FileEvent;
  
  public class Server {
      private ServerSocket serverSocket = null;
      private Socket socket = null;
      private ObjectInputStream inputStream = null;
      private FileEvent fileEvent;
      private File dstFile = null;
      private FileOutputStream fileOutputStream = null;
  
     public Server() {
  
      }
  
      /**
       * Accepts socket connection
       */
      public void doConnect() {
          try {
              serverSocket = new ServerSocket(4445);
              socket = serverSocket.accept();
              inputStream = new ObjectInputStream(socket.getInputStream());
          } catch (IOException e) {
              e.printStackTrace();
          }
      }
  
      /**
       * Reading the FileEvent object and copying the file to disk.
       */
      public void downloadFile() {
          try {
              fileEvent = (FileEvent) inputStream.readObject();
              if (fileEvent.getStatus().equalsIgnoreCase("Error")) {
                  System.out.println("Error occurred ..So exiting");
                  System.exit(0);
              }
              String outputFile = fileEvent.getDestinationDirectory() + fileEvent.getFilename();
              if (!new File(fileEvent.getDestinationDirectory()).exists()) {
                  new File(fileEvent.getDestinationDirectory()).mkdirs();
              }
              dstFile = new File(outputFile);
              fileOutputStream = new FileOutputStream(dstFile);
              fileOutputStream.write(fileEvent.getFileData());
              fileOutputStream.flush();
              fileOutputStream.close();
              System.out.println("Output file : " + outputFile + " is successfully saved ");
              //Thread.sleep(0);
              //System.exit(0);
  
          } catch (IOException e) {
              e.printStackTrace();
          } catch (ClassNotFoundException e) {
              e.printStackTrace();
          } 
  
      }
  
      public static void main(String[] args) {
          Server server = new Server();
          server.doConnect();
          server.downloadFile();
      }
  }
  </code></pre>
  
  <p>CLIENT </p>
  
  <pre><code>package mmd.client;
  
  import java.io.*;
  import java.net.Socket;
  
  import mmd.filetransfer.FileEvent;
  
  
  public class Client {
      private Socket socket = null;
      private ObjectOutputStream outputStream = null;
      private boolean isConnected = false;
      private String sourceFilePath = "/home/jovan/Desktop/videot.mpg";
      private FileEvent fileEvent = null;
      private String destinationPath = "/home/jovan/Desktop/tp/";
  
      public Client() {
  
      }
  
      /**
       * Connect with server code running in local host or in any other host
       */
      public void connect() {
          while (!isConnected) {
              try {
                  socket = new Socket("localHost", 4445);
                  outputStream = new ObjectOutputStream(socket.getOutputStream());
                  isConnected = true;
  
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
      }
  
      public void sendFile()  {
          fileEvent = new FileEvent();
          String fileName = sourceFilePath.substring(sourceFilePath.lastIndexOf("/") + 1, sourceFilePath.length());
          String path = sourceFilePath.substring(0, sourceFilePath.lastIndexOf("/") + 1);
          fileEvent.setDestinationDirectory(destinationPath);
          fileEvent.setFilename(fileName);
          fileEvent.setSourceDirectory(sourceFilePath);
          File file = new File(sourceFilePath);
          if (file.isFile()) {
              try {
                  DataInputStream diStream = new DataInputStream(new FileInputStream(file));
                  long len = (int) file.length();
                  byte[] fileBytes = new byte[(int) len];
                  int read = 0;
                  int numRead = 0;
                  while (read &lt; fileBytes.length &amp;&amp; (numRead = diStream.read(fileBytes, read,
                          fileBytes.length - read)) &gt;= 0) {
                      read = read + numRead;
                  }
                  fileEvent.setFileSize(len);
                  fileEvent.setFileData(fileBytes);
                  fileEvent.setStatus("Success");
              } catch (Exception e) {
                  e.printStackTrace();
                  fileEvent.setStatus("Error");
              }
          } else {
              System.out.println("path specified is not pointing to a file");
              fileEvent.setStatus("Error");
          }
          //Now writing the FileEvent object to socket
          try {
              outputStream.writeObject(fileEvent);
              System.out.println("Done...Going to exit");
              Thread.sleep(0);
              //System.exit(0);
          } catch (IOException e) {
              e.printStackTrace();
          } catch (InterruptedException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          } 
  
      }
  
      /**
       * Sending FileEvent object.
       
       * @throws IOException */
  
  
      public static void main(String[] args){
          Client client = new Client();
          client.connect();
          client.sendFile();
          client.sendFile();
  
  
      }
  }
  </code></pre>
  
  <p>How to prevent this? </p>