利用JavaFX工具构建Reactive系统

// 可读-且可写
StringProperty name = new SimpleStringProperty("Emil"); 
// 只读
ObservableBooleanValue nameIsEmpty = name.isEmpty();

TextField fieldA = new TextField();
TextField fieldB = new TextField();
fieldA.prefWidthProperty().bind(fieldB.widthProperty());

List<String> otherList = Arrays.asList("foo", "bar", "bar");
ObservableList<String> list = FXCollections.observableList(otherList);

list.addListener((ListChangeListener.Change<? extends String> change) -> {
  System.out.println("Received event.");
  while (change.next()) {
    if (change.wasAdded()) {
      System.out.println(
        "Items " + change.getAddedSubList() + " was added.");
    }

    if (change.wasRemoved()) {
      System.out.println(
        "Items " + change.getRemoved() + " was removed.");
    }
  }
});

System.out.println("Old list: " + list);
list.set(1, "foo");
System.out.println("New list: " + list);

Old list: [foo, bar, bar]
Received event.
Items [foo] was added.
Items [bar] was removed.
New list: [foo, foo, bar]

TextField fileLocation = new TextField();
StringProperty location = fileLocation.textProperty();
Property<Path> path = new SimpleObjectProperty<>();
 
Bindings.bindBidirectional(location, path, new StringConverter<Path>() {
  @Override
  public String toString(Path path) {
    return path.toString();
  }
 
  @Override
  public Path fromString(String string) {
    return Paths.get(string);
  }
});

TextField first = new TextField();
TextField second = new TextField();
TextField mix  = new TextField();
 
mix.textProperty().bind(
  Bindings.when(
    first.lengthProperty().isEqualTo(second.lengthProperty())
  ).then(Bindings.createStringBinding(
    () -> {
      int length    = first.lengthProperty().get();
      String firstText = first.textProperty().get();
      String secondText = second.textProperty().get();
      char[] result   = new char[length * 2];
 
      for (int i = 0; i < length; i++) {
        result[i * 2]   = firstText.charAt(i);
        result[i * 2 + 1] = secondText.charAt(i);
      }
 
      return new String(result);
    }, 
    first.textProperty(),
    second.textProperty()
  )).otherwise("Please enter two strings of exactly the same length.")
);