Module hw06
Package provided.utils.dispatcher

Interface IDispatcher<TMsg>

Type Parameters:
TMsg - The type of message to send to all the observers.
All Known Implementing Classes:
ADispatcher, ParallelDispatcher, SequentialDispatcher
public interface IDispatcher<TMsg>
Top-level abstraction of a Dispatcher which is the Observable in the Observer-Observable Design Pattern without the requirement to set the state before sending a message to the observers. A Dispatcher sends IMsg-type messages to all its observers which therefore must be capable of receiving and processing those messages, i.e. are IObserver<TMSg>. To maximally decouple an application from the randomizer's implementation any variable representing a randomizer should be typed to this interface, not to any concrete implementation. For example: IDispatcher<Graphics> myDispatcher = new SequentialDispatcher<Graphics>()
Author:
swong

  • Method Details

    • addObserver

      boolean addObserver​(IObserver<TMsg> obs)
      Add an observer to the dispatcher. If the observer is already in the dispatcher, as determined by the comparison (equals()) process, the dispatcher is NOT mutated and false is returned.
      Parameters:
      obs - The IObserver to add
      Returns:
      true if the given observer was not already in the dispatcher, false otherwise.
      Throws:
      ClassCastException - If the observer cannot be properly compared against the existing observers
      NullPointerException - If the supplied value is null

    • removeObserver

      IObserver<TMsg> removeObserver​(IObserver<TMsg> obs)
      Remove an observer from the dispatcher. The dispatcher does not make any assumptions that the observer being removed is identically the same object as that it was requested to remove via the input parameter. The returned object is the object that was internally held by the dispatcher.
      Parameters:
      obs - The IObserver to add
      Returns:
      The observer that was removed or null if it was not found.

    • getAllObservers

      Set<IObserver<TMsg>> getAllObservers()
      Get a COPY of the set of all the observers currently in the dispatcher. This is a shallow copy, so the observers themselves are not copied.
      Returns:
      A set of IObservers

    • removeAllObservers

      Set<IObserver<TMsg>> removeAllObservers()
      Removes all the observers currently in the dispatcher
      Returns:
      A COPY of the set of IObservers in the dispatcher before they were all removed.

    • updateAll

      void updateAll​(TMsg msg)
      Send the given message to all the observers in the dispatcher
      Parameters:
      msg - The IMsg to send to all the observers