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closing a socket

BrindleFly asked
Medium Priority
Last Modified: 2010-03-30
I have a very basic question: how can I test a Socket to determine whether or not it is open?

I know I receive an exception if the socket is unexpectedly closed.  I also know I receive a known return code (e.g. null) if I read or write to a closed socket.  But how do I ask a Socket whether or not it is open without having to read or write?


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I didnt find any way to do this (as per my knowledge). The best way to handle this is

After you say
InputStream is = socket.getInputStream();
create a push back input stream
PushbackInputStream ps = new PushBackInputStream (ps);

use ps instead of is to read data from socket.

Write an utility routine to test for socket closure as below

public static boolean isSocketClosed(PushbackInputStream pInpStr) throws Exception
        int rd;
        try { rd  = pInpStr.read(); } catch (Exception e) { System.out.println("Socket closed !!"); return true; }
        System.out.println("not yet closed!!");
        return false;

Do you mean to test if a socket is still valid?

// start

Socket mysocket = new Socket(hostname,portnum);

// Test if socket is valid
if(mysocket = null) {
    // socket closed, do something
} else {
    // socket open, read or write using socket

// end
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