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 Summary

Modifier and Type	Method	Description
void	close()
static NetworkTableListener	createConnectionListener(NetworkTableInstance inst, boolean immediateNotify, Consumer<NetworkTableEvent> listener)	Create a connection listener.
static NetworkTableListener	createListener(MultiSubscriber subscriber, EnumSet<NetworkTableEvent.Kind> eventKinds, Consumer<NetworkTableEvent> listener)	Create a listener for topic changes on a subscriber.
static NetworkTableListener	createListener(NetworkTableEntry entry, EnumSet<NetworkTableEvent.Kind> eventKinds, Consumer<NetworkTableEvent> listener)	Create a listener for topic changes on an entry.
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.
static NetworkTableListener	createListener(Subscriber subscriber, EnumSet<NetworkTableEvent.Kind> eventKinds, Consumer<NetworkTableEvent> listener)	Create a listener for topic changes on a subscriber.
static NetworkTableListener	createListener(Topic topic, EnumSet<NetworkTableEvent.Kind> eventKinds, Consumer<NetworkTableEvent> listener)	Create a listener for changes on a particular topic.
static NetworkTableListener	createLogger(NetworkTableInstance inst, int minLevel, int maxLevel, Consumer<NetworkTableEvent> listener)	Create a listener for log messages.
static NetworkTableListener	createTimeSyncListener(NetworkTableInstance inst, boolean immediateNotify, Consumer<NetworkTableEvent> listener)	Create a time synchronization listener.
int	getHandle()	Gets the native handle.
boolean	isValid()	Determines if the native handle is valid.
boolean	waitForQueue(double timeout)	Wait for the topic listener queue to be empty.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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.