Interface PacketListener

  • All Superinterfaces:
    All Known Implementing Classes:
    InterruptDialog, MathematicaTask, PacketPrinter

    public interface PacketListener
    extends java.util.EventListener
    The listener interface for receiving PacketArrivedEvents.

    Objects of classes that implement this interface can be registered with a KernelLink to receive notifications when packets arrive on the link. For each packet that arrives, the packetArrived() method will be invoked and passed a PacketArrivedEvent that describes the packet and lets you read its contents. Your packetArrived() method can consume or ignore the packet without affecting the internal packet loop in any way. You won't interfere with anything whether you read none, some, or all of the packet contents.

    Here is a trivial packetArrived() method, whichs only looks for TextPackets so that it can write their contents to System.out:

         public boolean packetArrived(PacketArrivedEvent evt) throws MathLinkException {
             if (evt.getPktType() == MathLink.TEXTPKT) {
                 KernelLink ml = (KernelLink) evt.getSource();
             return true;
    At the point that packetArrived is called, the packet has already been "opened" with nextPacket(), so your code can begin reading the packet contents immediately.

    Very advanced programmers can optionally indicate that the internal packet loop should not see the packet. This is done by returning false from packetArrived().

    See Also:
    PacketArrivedEvent, PacketPrinter, KernelLink
    • Method Detail

      • packetArrived

        boolean packetArrived​(PacketArrivedEvent evt)
                       throws MathLinkException
        Called when a packet arrives.

        Your implementation can read some or all of the packet contents, or ignore it completely, without affecting the internal packet loop. In other words, you do not need to make sure that you fully read the contents.

        Return true in normal circumstances. Programmers with special knowledge of the internal workings of the packet loop can choose to return false to indicate that this packet should not be seen by any additional PacketListeners or J/Link's internal packet handling.

        evt - the PacketArrivedEvent