Package edu.wpi.first.networktables

Class NetworkTableListener

java.lang.Object
edu.wpi.first.networktables.NetworkTableListener
All Implemented Interfaces:
AutoCloseable
public final class NetworkTableListener extends Object implements AutoCloseable
Event listener. This calls back to a callback function when an event matching the specified mask occurs. The callback function is called asynchronously on a separate thread, so it's important to use synchronization or atomics when accessing any shared state from the callback function.

  • Method Details

    • createListener

      public static NetworkTableListener createListener(NetworkTableInstance inst, String[] prefixes, EnumSet<NetworkTableEvent.Kind> eventKinds, Consumer<NetworkTableEvent> listener)
      Create a listener for changes to topics with names that start with any of the given prefixes. This creates a corresponding internal subscriber with the lifetime of the listener.
      Parameters:
      inst - Instance
      prefixes - Topic name string prefixes
      eventKinds - set of event kinds to listen to
      listener - Listener function
      Returns:
      Listener

    • createListener

      public static NetworkTableListener createListener(Topic topic, EnumSet<NetworkTableEvent.Kind> eventKinds, Consumer<NetworkTableEvent> listener)
      Create a listener for changes on a particular topic. This creates a corresponding internal subscriber with the lifetime of the listener.
      Parameters:
      topic - Topic
      eventKinds - set of event kinds to listen to
      listener - Listener function
      Returns:
      Listener

    • createListener

      public static NetworkTableListener createListener(Subscriber subscriber, EnumSet<NetworkTableEvent.Kind> eventKinds, Consumer<NetworkTableEvent> listener)
      Create a listener for topic changes on a subscriber. This does NOT keep the subscriber active.
      Parameters:
      subscriber - Subscriber
      eventKinds - set of event kinds to listen to
      listener - Listener function
      Returns:
      Listener

    • createListener

      public static NetworkTableListener createListener(MultiSubscriber subscriber, EnumSet<NetworkTableEvent.Kind> eventKinds, Consumer<NetworkTableEvent> listener)
      Create a listener for topic changes on a subscriber. This does NOT keep the subscriber active.
      Parameters:
      subscriber - Subscriber
      eventKinds - set of event kinds to listen to
      listener - Listener function
      Returns:
      Listener

    • createListener

      public static NetworkTableListener createListener(NetworkTableEntry entry, EnumSet<NetworkTableEvent.Kind> eventKinds, Consumer<NetworkTableEvent> listener)
      Create a listener for topic changes on an entry.
      Parameters:
      entry - Entry
      eventKinds - set of event kinds to listen to
      listener - Listener function
      Returns:
      Listener

    • createConnectionListener

      public static NetworkTableListener createConnectionListener(NetworkTableInstance inst, boolean immediateNotify, Consumer<NetworkTableEvent> listener)
      Create a connection listener.
      Parameters:
      inst - instance
      immediateNotify - notify listener of all existing connections
      listener - listener function
      Returns:
      Listener

    • createTimeSyncListener

      public static NetworkTableListener createTimeSyncListener(NetworkTableInstance inst, boolean immediateNotify, Consumer<NetworkTableEvent> listener)
      Create a time synchronization listener.
      Parameters:
      inst - instance
      immediateNotify - notify listener of current time synchronization value
      listener - listener function
      Returns:
      Listener

    • createLogger

      public static NetworkTableListener createLogger(NetworkTableInstance inst, int minLevel, int maxLevel, Consumer<NetworkTableEvent> listener)
      Create a listener for log messages. By default, log messages are sent to stderr; this function sends log messages with the specified levels to the provided callback function instead. The callback function will only be called for log messages with level greater than or equal to minLevel and less than or equal to maxLevel; messages outside this range will be silently ignored.
      Parameters:
      inst - instance
      minLevel - minimum log level
      maxLevel - maximum log level
      listener - listener function
      Returns:
      Listener

    • close

      public void close()
      Specified by:
      close in interface AutoCloseable

    • isValid

      public boolean isValid()
      Determines if the native handle is valid.
      Returns:
      True if the native handle is valid, false otherwise.

    • getHandle

      public int getHandle()
      Gets the native handle.
      Returns:
      Native handle

    • waitForQueue

      public boolean waitForQueue(double timeout)
      Wait for the topic listener queue to be empty. This is primarily useful for deterministic testing. This blocks until either the topic listener queue is empty (e.g. there are no more events that need to be passed along to callbacks or poll queues) or the timeout expires.
      Parameters:
      timeout - timeout, in seconds. Set to 0 for non-blocking behavior, or a negative value to block indefinitely
      Returns:
      False if timed out, otherwise true.