How do i close a CommPort in RXTX

I am trying to close a Comm port using this:

public synchronized void closeComportButtonActionPerformed(
                java.awt.event.ActionEvent evt)  {

            try {
                twoWaySerCom.disconnect();
            } catch (Exception e) {

                e.printStackTrace();
            }
        } 

and my disconnect is this:

 void disconnect() throws Exception {
    if (serialPort != null) {
        InputStream in = serialPort.getInputStream();
        OutputStream out = serialPort.getOutputStream();
        try {

            // close the i/o streams.
            in.close();
            out.close();
        } catch (IOException ex) {
            // don't care
        }
        // Close the port.
        serialPort.close();
    }

When i press the close button my app is just freezing and i eventually get an error in my console saying:

A fatal error has been detected by the Java Runtime Environment:

#  EXCEPTION_ACCESS_VIOLATION (0xc0000005) at pc=0x00949e69, pid=7568,      tid=4724
#
# JRE version: Java(TM) SE Runtime Environment (8.0_25-b18) (build 1.8.0_25-b18)
# Java VM: Java HotSpot(TM) Client VM (25.25-b02 mixed mode, sharing windows-x86 )
# Problematic frame:
# C  [rxtxSerial.dll+0x9e69]

Can anyone explain what i have done wrong here? Thanks

This was partially resolved with the below. I can now successfully close the port once. If i re-open te port and then attempt to close it a second time then the same error occurs.

try {

            serialPort.removeEventListener();
            serialPort.close();            
            in.close();
            out.close();
        } catch (IOException ex) {
            // don't care
        }
        // Close the port.
        serialPort.close();
    }