Package eu.webtoolkit.jwt

Class EventSignal1<E extends WAbstractEvent>

  • public final class EventSignal1<E extends WAbstractEvent>
extends AbstractEventSignal
    A signal which relays a browser event that passes event details. The signal also passes on an event object that provides details of the event.

    • Method Detail

      • addListener

        public AbstractSignal.Connection addListener​(WObject listenerOwner,
                                             Signal1.Listener<E> listener)
        Adds a listener for this signal. Each listener will be triggered whenever the signal is triggered.
        Parameters:
        listenerOwner - the enclosing object for a listener implemented by an anonymous inner class.
        listener - the listener
        Returns:
        a connection object that may be used to control the connection
        See Also:
        addListener(WObject, Signal.Listener)

      • getListenerCount

        protected int getListenerCount()
        Description copied from class: AbstractSignal
        Returns the number of connected listeners.
        Overrides:
        getListenerCount in class AbstractEventSignal
        Returns:
        the number of connected listeners.

      • removeListener

        public void removeListener​(Signal1.Listener<E> listener)
        Removes a listener.
        Parameters:
        listener - a listener that was previously added

      • trigger

        public void trigger​(E event)
        Triggers the signal. Event details will be passed on to listeners.
        Parameters:
        event - The event details.

      • addListener

        public AbstractSignal.Connection addListener​(WObject listenerOwner,
                                             Signal.Listener listener)
        Description copied from class: AbstractSignal
        Adds a listener for this signal.

        Each listener will be notified when the signal is triggered.

        An owner object may be passed when the listener is implemented using an (anonymous) inner class. In that case the owner object should be the enclosing object of the listener object, and this is used to bind the lifetime of the listener. To avoid the owner object from not being garbage collected when it is no longer used, only the owner object will add a reference to the listener, while the signal will use a weak reference.

        This avoids the most common reason for memory leaks in Java implementations of the Observer pattern: the owner object will not get garbage collected because of the (anonymous) listener object having a reference to it, even if the receiver object is no longer referenced from anywhere. When the owner object is not null, the listener is stored using a strong reference in the owner object, and using a weak reference in the signal.

        Specified by:
        addListener in class AbstractSignal
        Parameters:
        listenerOwner - if not null, the enclosing object for a listener implemented using an inner class
        listener - the listener
        Returns:
        a connection object that may be used to control the connection