Sockets in ArrayList wont get closed

Question

So i have this application in which I am storing Sockets in an ArrayList on the Server side. When the client closes its application the socket must close as well but It doesnt reflect the changes in the ArrayList in the server.

class arrays
{
    public static ArrayList<Socket> online_buyer=new ArrayList<Socket>(); 
    public static ArrayList<Socket> online_seller=new ArrayList<Socket>(); 
        public static ArrayList<String> buyer_prod=new ArrayList<String>();

}

    public void seller_display()
    {
        while(true)
        {   


            if(flag==1)
            {

                synchronized(sock)
                {
                for(int i=0;i<arrays.online_buyer.size();i++)
                {
                System.out.println(arrays.buyer_prod.get(i));
                }
                flag=0;
                }
            }


            check2();

        }

    }


    public void check2()
    {
        for(int i=0;i<arrays.online_buyer.size();i++)
        {
            try 
            {
            Thread.sleep(1000);
            } 
            catch (InterruptedException e) 
            {
            e.printStackTrace();
            }
            **while(!arrays.online_buyer.get(i).isConnected())** 
            {
                arrays.online_buyer.remove(i);
                arrays.buyer_user.remove(i);
                arrays.buyer_add.remove(i);
                arrays.buyer_prod.remove(i);
                arrays.time.remove(i);
                arrays.buyer_no.remove(i);
                flag=1;
                System.out.println("RECORD DELETED");
            }


        }

    }


public void run()
    {
    get_details();

    }
}

Now the statement while(!arrays.online_buyer.get(i).isConnected()) must be while(!false)=true. When i close the socket from the client side as isconnected()method must return false. But this statement never runs to be false even if i close the socket from client.

TCP to the rescue! The server can't detect a closed connection unless it is trying to read or write to it. — Thomas Jungblut, Jun 04 '14 at 10:18
Can your question be boiled down to "why does `socket.isConnected()` return `true` even after the client closed the connection"? — chiccodoro, Jun 04 '14 at 10:19
As far as I remember you will not notice a client close event in the `isConnected` state but by an EOF signal in the input stream. — chiccodoro, Jun 04 '14 at 10:19
@rmuller : This is just a part of code. The whole code was pretty huge. It compiles fine — Kartik Gupta, Jun 04 '14 at 10:20
@ThomasJungblut : So the isconnected() connection is Useless? — Kartik Gupta, Jun 04 '14 at 10:21
@user3686725 AFAIK the isconnected turns to false when the *server* closes the connection. — chiccodoro, Jun 04 '14 at 10:23
@chiccodoro It returns `false` when the *local application* closes the *socket.* It has nothing to do with the state of the *connection* whatsoever. Whether the 'local application' is the server or the client has nothing to do with it. — user207421, Jun 04 '14 at 10:25

score 1 · Answer 1 · answered Jun 04 '14 at 10:21

1

When I close the socket from the client side as isConnected() method must return false.

No it mustn't. Where does it say that?

The reality of this is that isConnected() returns true if you have ever connected this Socket, which you have. The correct way to detect peer termination is as follows:

read() returns -1
readLine() returns null
readXXX() throws EOFException for any other XXX
write() throws IOException

answered Jun 04 '14 at 10:21

user207421

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Thanks man. They should have named the method was everconnected – Kartik Gupta Jun 04 '14 at 10:45
'Returns the connection state *of the socket*' is clear enough, but I would agree they should have added warnings about *not of the connection* to both this and `isClosed().` – user207421 Jun 04 '14 at 10:55

Sockets in ArrayList wont get closed

1 Answers1