java.lang.NullPointerException at ServerSocker.accept()

Question

I am getting the following exception:

java.lang.NullPointerException at
 gr.test.asterisk.AsteriskServerSocket.run(AsteriskServerSocket.java:72)

Here's my code:

public class AsteriskServerSocket  extends Thread{

    private Socket server = null;
    private ServerSocket serverSocket = null;
    private String serverPortString = null;

    public AsteriskServerSocket(){
         serverPortString = "50050";

        try {
            serverSocket = new ServerSocket(Integer.parseInt(serverPortString));
            serverSocket.setSoTimeout(1000000000);
        } catch (SocketTimeoutException s) {
            WriteExceptions.writeToFile(s);
        } catch (IOException e) {
            WriteExceptions.writeToFile(e);
        }
    }

    public void run() {
        while (true) {
            try {
                server = serverSocket.accept();<---- This is the line which I get the exception
                ......
            }
            } catch (SocketTimeoutException s) {
                System.err.println("Σφάλμα στην Server run. Socket timed out. \n" + s);
                break;
            } catch (IOException e) {
                System.err.println("Σφάλμα στην Server run.\n" + e);
                break;
            }
        }
    }
}

And AsteriskServerSocket, I call it in the Main Class:

public static void main(String[] args) {
    AsteriskServerSocket aSS = new AsteriskServerSocket();
}

My Operating System is CentOS release 5.10 (Final) and my JDK version is 1.8.0_45. I don't know why this exception is thrown. Am I missing something here?

My exceptions in the constructor is:

My exception in the constructor is 0 :java.net.BindException: Address already in use at java.net.PlainSocketImpl.socketBind(Native Method) at java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:382) at java.net.ServerSocket.bind(ServerSocket.java:375) at java.net.ServerSocket.(ServerSocket.java:237) at java.net.ServerSocket.(ServerSocket.java:128)

if you want very large timeout, just give a 0. A timeout of zero is interpreted as an infinite timeout. docs.oracle.com/javase/7/docs/api/java/net/… — Mecon
– Mecon, Commented May 13, 2015 at 17:32

Necreaux · Accepted Answer · 2015-05-13 17:25:51Z

1

You are ignoring exceptions in the constructor and writing them to the logs, therefore serverSocket is null. Check the logs and/or rethrow those exceptions.

answered May 13, 2015 at 17:25

Necreaux

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3 Comments

KostasC Over a year ago

Thanks for your advise! I will follow it and came back with the results.

KostasC Over a year ago

My exception in the constructor is 0 :java.net.BindException: Address already in use at java.net.PlainSocketImpl.socketBind(Native Method) at java.net.AbstractPlainSocketImpl.bind(AbstractPlainSocketImpl.java:382) at java.net.ServerSocket.bind(ServerSocket.java:375) at java.net.ServerSocket.<init>(ServerSocket.java:237) at java.net.ServerSocket.<init>(ServerSocket.java:128)

Necreaux Over a year ago

Something else is already using that port. Either kill the other application or use a different port. Two applications cannot use a single port.

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