tornadofx-guide

Dependency Injection
Dependency Injection
View and Controller are singletons, so you need some way to access the instance of a
specific component. Tornado FX supports dependency injection, but you can also lookup
components with the find function.
val myController = find(MyController::class)
When you call find , the component corresponding to the given class is looked up in a
global component registry. If it did not exist prior to the call, it will be created and inserted
into the registry before the function returns.
If you want to declare the controller referance as a field member however, you should use
the inject delegate instead. This is a lazy mechanism, so the actual instance will only be
created the first time you call a function on the injected resource. Using inject is always
prefered, as it allows your components to have circular dependencies.
val myController: MyController by inject()
Third party injection frameworks
TornadoFX makes it easy to inject resources from a third party dependency injection
framework, like for example Guice or Spring. All you have to do is implement the very simple
DIContainer interface when you start your application. Let's say you have a Guice module
configured with a fictive HelloService . Start Guice in the init block of your App class
and register the module with TornadoFX:
val guice = Guice.createInjector(MyModule())
FX.dicontainer = object : DIContainer {
override fun getInstance(type: KClass)
= guice.getInstance(type.java)
}
The DIContainer implementation is configured to delegate lookups to
guice.getInstance
To inject the HelloService configured in MyModule , use the di delegate instead of the
inject delegate:
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