Question

I’m trying to read an object from client program over tcp. As you can see in this line I created objectInput:

ObjectInputStream objectInput = new ObjectInputStream(incoming.getInputStream());

And then read my input from the other program. It used to work fine until i made minor changes to clean up the program. Personally Assume I added

objectInput.clsoe();

My question is, After reading the object should I close the objectInputStream or Keep remain without close? Should I close it straight away after using it or at the end of if block or at the end of program? What are the effect of the close? By the way I have read the close documentation.

Here is the error:

java.io.EOFException
    at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2280)
    at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:2749)
    at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:779)
    at java.io.ObjectInputStream.<init>(ObjectInputStream.java:279)
    at Server.ClientWorker.run(MyCollectionServer.java:116)
    at java.lang.Thread.run(Thread.java:680)

Here is my code:

    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        try 
        {
            serverSocket = new ServerSocket(port);  
        } 
        catch (IOException e) 
                {
            e.printStackTrace();
        }
        while(true)
        {   
            ClientWorker w;
            try
            {   
                w = new ClientWorker(serverSocket.accept());
                Thread t = new Thread(w);
                t.start();
            }
            catch(IOException e)
            {
                e.printStackTrace();
                break;
            }   
        }
    }
}

class ClientWorker implements Runnable
{
.....
    private Socket incoming;
    public ClientWorker(Socket incoming)
    {
        myList = new ArrayList<PureAlbum>();
        loadList();
        this.incoming = incoming;
    }

.....
    public synchronized  void run()
    {

else if(request.compareTo("AddAlbum")==0)
        {
            try
            {
                ObjectInputStream objectInput = new ObjectInputStream(incoming.getInputStream()); //This is the line mentioned in the error
                PureAlbum object = (PureAlbum) objectInput.readObject();


                if(object instanceof CDAlbum)
                {
                    CDAlbum a = (CDAlbum) object;
                    myList.add(a);
                    System.out.println("Artist = " + a.getArtist());
                }
                else if(object instanceof Client.au.edu.uow.Collection.DVDAlbum)
                {
                    myList.add((DVDAlbum) object);              
                }
                else
                {
                    System.err.println("Warning : The object to add to database is unknown! "+ object.getClass() + "*");
                    System.exit(0);
                }


            }
            catch (UnknownHostException e) 
            {
                System.err.println("Can not read the host name");
                e.printStackTrace();
            } 
            catch (IOException e) 
            {
                System.err.println("Can not read the FILE name"); //This exception has been called
                e.printStackTrace(); 
            }
            catch (ClassNotFoundException e) 
            {
                e.printStackTrace();
            }
        }

Answer 1

This line of stack trace shows that the exception is occurring when you are initializing the ObjectInputStream, not when you are closing.

at java.io.ObjectInputStream.<init>(ObjectInputStream.java:279)

The most likely cause is that the remote client did not open an ObjectOutputStream. It might have written some other kind of data, or it might have closed its output stream or simply exited.