KEvents

Simple yet powerful Java Events library to implement Event-Driven logic in your project.

Creating first event

To make event class, simple annotate your class as Event

public class YourEvent implements Event {
     private final String message;
     
     public YourEvent(String message) {
         this.message = message;
     }
     
     public String getMessage() {
         return message;
     }
}

Now let's create listener, where we will handle our event: Sure, you can handle more than 1 event in one listener.

To make Listener class simply annotate it as listener.

public class YourListener implements Listener {
     @EventHandler
     public void onYourEvent(YourEvent e) {
         System.out.println(e.getMessage());
     }
}

Firing created event

After you have created your event, let's create EventManager instance;

public static void main(String[] args) {
    EventManager eventManager = new EventManager();
    eventManager.registerListener(new YourListener()); //Registers your listener class
    
    YourEvent event = new YourEvent("Message");
    
    eventManager.call(event); // prints "Message", as specified in Listener.
    
    eventManager.close();
}

If you have more arguments in the function, simply add them to call method of event manager.

@EventHandler
public void onYourEvent(YourEvent e, int yourArg1, String yourArg2) {
    //do smth
}

eventManager.call(new YourEvent(), 5, "Yet another arg")

Typed Events

To create an event, calling which you should get a value, specify return value class in @Event annotation. Note that if the return type you define has a primitive alternative, the primitive return type in the function should be used (like if you specify Integer.class, create method with int return type) The same works with Void type (if you specify Void.class explicitly, use void return type)

@TypeNames(String.class)
public class SomeEvent implements Event {
    
}

Great example:

@TypeNames(String.class)
class SomeEvent {}

class SampleListener implements Listener {

    @EventHandler(priority = EventPriority.HIGH)
    public String onSomeEvent(SomeEvent e) {
        return "Hello";
    }

    @EventHandler
    public String onAnotherSample(SomeEvent e) {
        return "World";
    }
    
    public class SampleEventCall {
        public static void main(String[] args) {
            try (var manager = new EventManager()) {
                manager.registerListener(new SampleListener());

                CallResult result = manager.call(new SomeEvent());
                List<String> values = result.getValues(String.class); // Get value list with type of String
                
                String message = String.join(" ", result.getValues(String.class));

                System.out.println(message); //Hello world
            }
        }
    }
}

Here we specified 2 event handlers with return values. To specify the right order of execution, simply pass EventPriority to annotation arguments.

In case you have only one typed event handler you can simply call CallResult#first(Class) method;

CallResult result = eventManager.call(new SampleEvent());
String stringValue = result.first(String.class);

Multi-Typed events

You can specify more than 1 return type to event. To specify multiple event types pass an array of type classes to your event annotation.

@TypeNames(typeNames = {String.class, Integer.class})
public class YourEvent implements Event {}

Then to get values of specific type simply call getValues method for list of values or first method for the first result. For instance, to get integers:

CallResult#getValues(Integer.class) //All Integer values
CallResult#first(String.class) //First String value

Scheduling events

Events can be scheduled by calling schedule method of EventManager object.

CompletableFuture<CallResult> result = eventManager.schedule(new YourEvent(), 1000L); //1000L =  delay 1000 ms before firing event

Cancelling events

Simply implement Cancellable interface to your event and furthermore call setCancelled(true/false) method;

public class YourEvent implements Event, Cancellable {
    private boolean cancelled = false;

    @Override
    public boolean isCancelled() {
        return cancelled;
    }

    @Override
    public void setCancelled(boolean cancelled) {
        this.cancelled = true;
    }
}

public class YourListener implements Listener {
    @EventHandler(priority = EventPriority.HIGH)
    public void onYourEvent(YourEvent e) {
        System.out.println("Cancelling event");
        e.setCancelled(true);
    }
    
    @EventHandler
    public void onSameYourEvent(YourEvent e) {
        System.out.println("Will not be printed");
    }
}

If you need specific method to be executed even after the event was cancelled, specify ignoreCancelled argument in EventHandler annotation.

    @EventHandler(ignoreCancelled = true)
    public void onSameYourEvent(YourEvent e) {
        System.out.println("Now will be printed");
    }

TODO:

1. Add project to maven repository.
2. Create detailed examples.