"Stream closed" IOException in client-server application using java socket

Question

my client breaks, because of "Stream closed" exception. Server properly waits for connection, but client don't send any data because of "stream closed" Exception. Server after waiting time echoes "Unexpected error".

Thanks for help!

My code:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
    private static final int PORT = 50000;
    static boolean flaga = true;

    private static ServerSocket serverSocket;
    private static Socket clientSocket;

    public static void main(String[] args) throws IOException {
        serverSocket = null;
        try {
            serverSocket = new ServerSocket(PORT);
        } catch (IOException e) {
            System.err.println("Could not listen on port: " + PORT);
            System.exit(1);
        }

        System.out.print("Wating for connection...");

        Thread t = new Thread(new Runnable() {
            public void run() {
                try {
                    while (flaga) {
                        System.out.print(".");
                        Thread.sleep(1000);
                    }
                } catch (InterruptedException ie) {
                    //
                }

                System.out.println("\nClient connected on port " + PORT);
            }
        });
        t.start();

        clientSocket = null;
        try {
            clientSocket = serverSocket.accept();
            flaga = false;
        } catch (IOException e) {
            System.err.println("Accept failed.");
            t.interrupt();
            System.exit(1);
        }

        final PrintWriter out = new PrintWriter(clientSocket.getOutputStream(),
                true);
        final BufferedReader in = new BufferedReader(new InputStreamReader(
                clientSocket.getInputStream()));

        t = new Thread(new Runnable() {
            public void run() {
                try {
                    Thread.sleep(5000);

                    while (true) {
                        out.println("Ping");
                        System.out.println(System.currentTimeMillis()
                                + " Ping sent");

                        String input = in.readLine();

                        if (input.equals("Pong")) {
                            System.out.println(System.currentTimeMillis()
                                    + " Pong received");
                        } else {
                            System.out.println(System.currentTimeMillis()
                                    + " Wrong answer");
                        }

                        Thread.sleep(5000);
                    }
                } catch (Exception e) {
                    System.err.println(System.currentTimeMillis()
                            + " Unexpected Error");
                }
            }
        });
        t.start();
    }
}

And Client code:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

public class Client {
    private static final int PORT = 50000;
    private static final String HOST = "127.0.0.1";

    public static void main(String[] args) throws IOException {
        Socket socket = null;

        try {
            socket = new Socket(HOST, PORT);
        } catch (Exception e) {
            System.err.println("Could not connect to " + HOST + ":" + PORT);
            System.exit(1);
        }

        final PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
        final BufferedReader in = new BufferedReader(new InputStreamReader(
                socket.getInputStream()));

        Thread t = new Thread(new Runnable() {
            public void run() {
                long start = System.currentTimeMillis();

                try {
                    while (true) {
                        try {
                            String input = in.readLine();

                            if (input != null) {
                                System.out.println(System.currentTimeMillis()
                                        + " Server: " + input);
                            }

                            if (input.equals("Ping")) {
                                if (System.currentTimeMillis() - start > 30000) {
                                    out.println("Pon g");
                                    System.out.println(System
                                            .currentTimeMillis()
                                            + " Client: Pon g");
                                    break;
                                }

                                out.println("Pong");
                                System.out.println(System.currentTimeMillis()
                                        + " Client: Pong");
                            } else {
                                System.out.println(start);
                                out.println("got");
                            }
                        } catch (IOException ioe) {
                            System.err.println(System.currentTimeMillis() + " "
                                    + ioe.getMessage());
                            ioe.getStackTrace();
                            System.exit(0);
                        }
                    }
                } catch (Exception e) {
                    System.err.println(System.currentTimeMillis()
                            + " Unexpected Error");
                }
            }
        });
        t.start();

        out.close();
        in.close();
        socket.close();
    }
}

Answer 1

In your client, you start the thread but directly close streams and socket:

t.start();
out.close();
in.close();
socket.close();

You can, as a test, move the stream and socket calls to the last catch block.

 ...
        } catch (Exception e) {
                System.err.println(System.currentTimeMillis()
                        + " Unexpected Error");     
                out.close();
                in.close();
                socket.close();
            }
        }
    });
    t.start();
}