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RxJava bindings for JavaFX
https://github.com/reactivex/rxjavafx

java javafx reactivex rxjava

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RxJava bindings for JavaFX

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# RxJavaFX: JavaFX bindings for RxJava



# NOTE: UNSUPPORTED, PLEASE FOLLOW FORKS FOR NEWER DEVELOPMENTS AND DEPLOYMENTS

https://github.com/torakiki/RxJavaFX



Read the free eBook [_Learning RxJava with JavaFX_](https://www.gitbook.com/book/thomasnield/rxjavafx-guide/details) to get started.



RxJavaFX is a lightweight library to convert JavaFX events into [RxJava](https://github.com/ReactiveX/RxJava) Observables/Flowables and vice versa. It also has a `Scheduler` to safely move emissions to the JavaFX Event Dispatch Thread. 



**NOTE**: To use with [Kotlin](http://kotlinlang.org/), check out [RxKotlinFX](https://github.com/thomasnield/RxKotlinFX) to leverage this library with extension functions and additional operators. 



## Master Build Status






## Documentation



[Learning RxJava with JavaFX](https://www.gitbook.com/book/thomasnield/rxjavafx-guide/details) - Free eBook that covers RxJava from a JavaFX perspective.



[Learning RxJava](https://www.packtpub.com/application-development/learning-rxjava) - Packt book covering RxJava 2.0 in depth, with a few RxJavaFX examples.



[![](https://dz13w8afd47il.cloudfront.net/sites/default/files/imagecache/ppv4_main_book_cover/9781787120426.jpg)](https://www.packtpub.com/application-development/learning-rxjava)



## 1.x Binaries



Binaries and dependency information for Maven, Ivy, Gradle and others can be found at [http://search.maven.org](http://search.maven.org/#search%7Cga%7C1%7Cio.reactivex.rxjavafx).



Example for Maven:



```xml



    io.reactivex

    rxjavafx

    1.x.y



```



Gradle: 



```groovy 

dependencies {

	compile 'io.reactivex:rxjavafx:1.x.y'

}

```



## 2.x Binaries



RxJavaFX 2.x versions uses a different group ID `io.reactivex.rxjava2` to prevent clashing with 1.x dependencies. Binaries and dependency information for Maven, Ivy, Gradle and others can be found at [http://search.maven.org](http://search.maven.org/#search%7Cga%7C1%7Cio.reactivex.rxjava2.rxjavafx).



Example for Maven:



```xml



    io.reactivex.rxjava2

    rxjavafx

    2.x.y



```



Gradle: 



```groovy 

dependencies {

	compile 'io.reactivex.rxjava2:rxjavafx:2.x.y'

}

```



## Features



RxJavaFX has a comprehensive set of features to interop RxJava with JavaFX:

- Factories to turn `Node`, `ObservableValue`, `ObservableList`, and other component events into an RxJava `Observable`

- Factories to turn an RxJava `Observable` or `Flowable` into a JavaFX `Binding`. 

- A scheduler for the JavaFX dispatch thread



### Node Events

You can get event emissions by calling `JavaFxObservable.eventsOf()` and pass the JavaFX `Node` and the `EventType` you are interested in.  This will return an RxJava `Observable`. 



```java

Button incrementBttn = new Button("Increment");



Observable bttnEvents =

        JavaFxObservable.eventsOf(incrementBttn, ActionEvent.ACTION);

```



### Action Events

Action events are common and do not only apply to `Node` types. They also emit from `MenuItem` and `ContextMenu` instances, as well as a few other types. 



Therefore, a few overloaded factories are provided to emit `ActionEvent` items from these controls



##### Button ActionEvents

```java

Button incrementBttn = new Button("Increment");



Observable bttnEvents =

        JavaFxObservable.actionEventsOf(incrementBttn);

```

##### MenuItem ActionEvents

```java

MenuItem menuItem = new MenuItem("Select me");



Observable menuItemEvents = 

        JavaFxObservable.actionEventsOf(menuItem);

```



### Other Event Factories



There are also factories provided to convert events from a `Dialog`, `Window` or `Scene` into an `Observable`. If you would like to see factories for other components and event types, please let us know or put in a PR. 



#### Dialogs and Alerts

```java

Alert alert = new Alert(AlertType.CONFIRMATION);

alert.setTitle("Confirmation");

alert.setHeaderText("Please confirm your action");

alert.setContentText("Are you ok with this?");



JavaFxObservable.fromDialog(alert)

    .filter(response -> response.equals(ButtonType.OK))

    .subscribe(System.out::println,Throwable::printStackTrace);

```



##### Emitting Scene Events



```java

Observable sceneMouseMovements =

     JavaFxObservable.eventsOf(scene, MouseEvent.MOUSE_MOVED);



sceneMouseMovements.subscribe(v -> System.out.println(v.getSceneX() + "," + v.getSceneY()));

```



##### Emitting Window Hiding Events

```java

 Observable windowHidingEvents =

    JavaFxObservable.eventsOf(primaryStage,WindowEvent.WINDOW_HIDING);



windowHidingEvents.subscribe(v -> System.out.println("Hiding!"));

```



### ObservableValue 

Not to be confused with the RxJava `Observable`, the JavaFX `ObservableValue` can be converted into an RxJava `Observable` that emits the initial value and all value changes. 



```java

TextField textInput = new TextField();



Observable textInputs =

        JavaFxObservable.valuesOf(textInput.textProperty());

```

Note that many Nodes in JavaFX will have an initial value, which sometimes can be `null`, and you might consider using RxJava's `skip()` operator to ignore this initial value. 



##### ObservableValue Changes



For every change to an `ObservableValue`, you can emit the old value and new value as a pair. The two values will be wrapped up in a `Change` class and you can access them via `getOldVal()` and `getNewVal()`. Just call the `JavaFxObservable.changesOf()` factory. 



```java

SpinnerValueFactory svf = new SpinnerValueFactory.IntegerSpinnerValueFactory(0, 100);

Spinner spinner = new Spinner<>();

spinner.setValueFactory(svf);

spinner.setEditable(true);



Label spinnerChangesLabel = new Label();

Subscription subscription = JavaFxObservable.changesOf(spinner.valueProperty())

        .map(change -> "OLD: " + change.getOldVal() + " NEW: " + change.getNewVal())

        .subscribe(spinnerChangesLabel::setText);

```



### ObservableList, ObservableMap, and ObservableSet



There are several factories to emit many useful `ObservableList`, `ObservableMap`, and `ObservableSet` events as Observables. These all can be found as static factory methods in the `JavaFxObservable` static class. 



|Factory Method|Parameter Type|Return Type|Description|

|---|---|---|---

|emitOnChanged()|ObservableList<T>|Observable<ObservableList<T>>|Emits the entire `ObservableList` every time it changes|

|additionsOf()|ObservableList<T>|Observable<T>|Emits additions to an `ObservableList`|

|removalsOf()|ObservableList<T>|Observable<T>|Emits removals from an `ObservableList`|

|updatesOf()|ObservableList<T>|Observable<ListChange<T>>|Emits every item that was the result of a change to an `ObservableList`, with an `ADDED`, `REMOVED`, or `UPDATED` flag|

|distinctChangesOf()|ObservableList<T>| Observable<ListChange<R>>|Emits only *distinct* addtions and removals to an `ObservableList`|

|distinctMappingsOf()|ObservableList<T>, Func1<T,R>| Observable<ListChange<R>>|Emits only *distinct* additions and removals to an `ObservableList` and emits the mapping|

|distinctChangesOf()|ObservableList<T>, Func1<T,R>| Observable<ListChange<R>>|Emits only *distinct* additions and removals to an `ObservableList` based on a mapping|

|emitOnChanged()|ObservableMap<K,T>|Observable<ObservableMap<K,T>>|Emits the entire `ObservableMap` every time it changes|

|additionsOf()|ObservableMap<K,T>|Observable<Map.Entry<K,T>>|Emits every `Map.Entry` added to an `ObservableMap`|

|removalsOf()|ObservableMap<K,T>|Observable<Map.Entry<K,T>>|Emits every `Map.Entry` removed from an `ObservableMap`|

|changesOf()|ObservableMap<K,T>|Observable<MapChange<K,T>>|Emits every key/value pair with an `ADDED` or `REMOVED` flag.|

|emitOnChanged()|ObservableSet<T>|Observable<ObservableSet<T>>|Emits the entire `ObservableSet` every time it changes|

|additionsOf()|ObservableSet<T>|Observable<T>|Emits every addition to an `ObservableSet`|

|removalsOf()|ObservableSet<T>|Observable<T>|Emits every removal to an `ObservableSet`|

|changesOf()|ObservableSet<T>|Observable<SetChange<T>|Emits every item `ADDED` or `REMOVED` item from an `ObservableSet` with the corresponding flag|



### Binding

You can convert an RxJava `Observable` into a JavaFX `Binding` by calling the `JavaFxObserver.toBinding()` factory. Calling the `dispose()` method on the `Binding` will handle the unsubscription from the `Observable`.  You can then take this `Binding` to bind other control properties to it. 



```java

Button incrementBttn = new Button("Increment");

Label incrementLabel =  new Label("");



Observable bttnEvents =

        JavaFxObservable.eventsOf(incrementBttn, ActionEvent.ACTION);

        

Observable accumulations = bttnEvents.map(e -> 1)

        .scan(0,(x, y) -> x + y)

        .map(Object::toString);

        

Binding binding = JavaFxObserver.toBinding(accumulations);



incrementLabel.textProperty().bind(binding);



//do stuff, then dispose Binding

binding.dispose();



```



It is usually good practice to specify an `onError` to the `Binding`, just like a normal `Observer` so you can handle any errors that are communicated up the chain. 



```

incrementLabel.textProperty().bind(binding, e -> e.printStackTrace());

```



### Lazy Binding



The `toBinding()` factory above will eagerly subscribe the `Observable` to the `Binding` implementation. But if you want to delay the subscription to the `Observable` until the `Binding` is actually used (specifically when its `getValue()` is called), use `toLazyBinding()` instead. 



```java

Binding lazyBinding = JavaFxObserver.toLazyBinding(myObservable);

```

This can be handy for data controls like `TableView`, which will only request values for records that are visible. Using the `toLazyBinding()` to feed column values will cause subscriptions to only happen with visible records. 



### CompositeBinding



You also have the option to use a `CompositeBinding` to group multiple `Binding`s together, and `dispose()` them all at once. It is the JavaFX equivalent to `CompositeSubscription`. 



```java

Binding binding1 = ...

bindings.add(binding1);



Binding binding2 = ... 

bindings.add(binding2);



//do stuff on UI, and dispose() both bindings

bindings.dispose();

```        



### JavaFX Scheduler



When you update any JavaFX control, it must be done on the JavaFX Event Dispatch Thread. Fortunately, the `JavaFxScheduler` makes it trivial to take work off the JavaFX thread and put it back when the results are ready.  Below we can use the `observeOn()` to pass text value emissions to a computation thread where the text will be flipped. Then we can pass `JavaFxScheduler.platform()` to another `observeOn()` afterwards to put it back on the JavaFX thread. From there it will update the `flippedTextLabel`.



```java

TextField textInput = new TextField();

Label fippedTextLabel = new Label();



Observable textInputs =

        JavaFxObservable.valuesOf(textInput.textProperty());



sub2 = textInputs.observeOn(Schedulers.computation())

        .map(s -> new StringBuilder(s).reverse().toString())

        .observeOn(JavaFxScheduler.platform())

        .subscribe(fippedTextLabel::setText);

```



### JavaFX Interval



There is a JavaFX equivalent to `Observable.interval()` that will emit on the JavaFX thread instead. Calling `JavaFxObservable.interval()` will push consecutive `Long` values at the specified `Duration`. 



```java

Observable everySecond = JavaFxObservable.interval(Duration.millis(1000));

```



## Differences from ReactFX

[ReactFX](https://github.com/TomasMikula/ReactFX) is a popular API to implement reactive patterns with JavaFX using the `EventStream`. However, RxJava uses an `Observable` and the two are not (directly) compatible with each other. 



Although ReactFX has some asynchronous operators like `threadBridge`, ReactFX emphasizes *synchronous* behavior. This means it encourages keeping events on the JavaFX thread. RxJavaFX, which fully embraces RxJava and *asynchronous* design, can switch between threads and schedulers with ease.  As long as subscriptions affecting the UI are observed on the JavaFX thread, you can leverage the powerful operators and libraries of RxJava safely.



If you are heavily dependent on RxJava, asynchronous processing, or do not want your entire reactive codebase to be UI-focused, you will probably want to use RxJavaFX. 



## Notes for Kotlin 

If you are building your JavaFX application with [Kotlin](https://kotlinlang.org/), check out [RxKotlinFX](https://github.com/thomasnield/RxKotlinFX) to leverage this library through Kotlin extension functions.



## Bugs and Feedback



For bugs, questions and discussions please use the [Github Issues](https://github.com/ReactiveX/RxJavaFX/issues).



 

## LICENSE



Licensed under the Apache License, Version 2.0 (the "License");

you may not use this file except in compliance with the License.

You may obtain a copy of the License at



Unless required by applicable law or agreed to in writing, software

distributed under the License is distributed on an "AS IS" BASIS,

WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

See the License for the specific language governing permissions and

limitations under the License.