event-bus/README.md

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# Event Bus
## Introduction
This library allows passing events between different objects without them having a direct reference to each other.
Any class can be made an event by implementing the `IEvent` interface.
Using an instance of the `EventBus` class, an instant of the event class can be dispatched.
This means that it will be forwarded to all listeners registered for it at the event bus.
In addition, a singleton instance of the event bus is provided by the `EventBus#getInstance()` method.
To listen to events, register event handling methods using the `Event` annotation.
For this to work, the method must have a return type of `void` and declare a single parameter of the desired event type.
Additionally, the class containing the method must implement the `EventListener` interface.
## A Simple Example
Lets look at a simple example: we declare the empty class `SimpleEvent` that implements `IEvent` and can thus be used as an event.
```java
import dev.kske.eventbus.IEvent;
public class SimpleEvent implements IEvent {}
```
Next, an event listener for the `SimpleEvent` is declared:
```java
import dev.kske.eventbus.*;
public class SimpleEventListener implements EventListener {
public SimpleEventListener() {
// Register this listener at the event bus
EventBus.getInstance().register(this);
// Dispatch a SimpleEvent
EventBus.getInstance().dispatch(new SimpleEvent());
}
@Event
private void onSimpleEvent(SimpleEvent event) {
System.out.println("SimpleEvent received!");
}
}
```
In this case, an event bus is created and used locally. In a more sophisticated example the class would acquire an external event bus that is used by multiple classes.
## Installation
Event Bus is currently hosted at [kske.dev](https://kske.dev).
To include it inside your project, just add the Maven repository and the dependency to your `pom.xml`:
```xml
<repositories>
<repository>
<id>kske-repo</id>
<url>https://kske.dev/maven-repo</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>dev.kske</groupId>
<artifactId>event-bus</artifactId>
<version>0.0.2</version>
</dependency>
</dependencies>
```