Package com.csse3200.game.events

Class EventHandler

java.lang.Object
com.csse3200.game.events.EventHandler
Direct Known Subclasses:
GameStateObserver
public class EventHandler extends Object
Send and receive events between objects. EventHandler provides an implementation of the Observer pattern, also known as an event system or publish/subscribe. When an event is triggered with trigger(), all listeners are notified of the event.

Currently supports up to 3 arguments for an event. More can be added, but consider instead passing a class with required fields.

If you get a ClassCastException from an event, trigger is being called with different arguments than the listeners expect.

  • Constructor Details

    • EventHandler

      public EventHandler()

  • Method Details

    • addListener

      public void addListener(String eventName, EventListener0 listener)
      Add a listener to an event with zero arguments
      Parameters:
      eventName - name of the event
      listener - function to call when event fires

    • addListener

      public <T> void addListener(String eventName, EventListener1<T> listener)
      Add a listener to an event with one argument
      Type Parameters:
      T - argument type
      Parameters:
      eventName - name of the event
      listener - function to call when event fires

    • addListener

      public <T0, T1> void addListener(String eventName, EventListener2<T0,T1> listener)
      Add a listener to an event with two arguments
      Type Parameters:
      T0 - Type of arg 0
      T1 - Type of arg 1
      Parameters:
      eventName - name of the event
      listener - function to call when event fires

    • addListener

      public <T0, T1, T2> void addListener(String eventName, EventListener3<T0,T1,T2> listener)
      Add a listener to an event with three arguments
      Type Parameters:
      T0 - Type of arg 0
      T1 - Type of arg 1
      T2 - Type of arg 2
      Parameters:
      eventName - name of the event
      listener - function to call when event fires

    • trigger

      public void trigger(String eventName)
      Trigger an event with no arguments
      Parameters:
      eventName - name of the event

    • trigger

      public <T> void trigger(String eventName, T arg0)
      Trigger an event with one argument
      Type Parameters:
      T - argument type
      Parameters:
      eventName - name of the event
      arg0 - arg to pass to event

    • trigger

      public <T0, T1> void trigger(String eventName, T0 arg0, T1 arg1)
      Trigger an event with one argument
      Type Parameters:
      T0 - Type of arg 0
      T1 - Type of arg 1
      Parameters:
      eventName - name of the event
      arg0 - arg 0 to pass to event
      arg1 - arg 1 to pass to event

    • trigger

      public <T0, T1, T2> void trigger(String eventName, T0 arg0, T1 arg1, T2 arg2)
      Trigger an event with one argument
      Type Parameters:
      T0 - Type of arg 0
      T1 - Type of arg 1
      T2 - Type of arg 2
      Parameters:
      eventName - name of the event
      arg0 - arg 0 to pass to event
      arg1 - arg 1 to pass to event
      arg2 - arg 2 to pass to event