JavaFX textfield binding - binding

Question

I have a textfield with a binding to a timestring like this:
timeStringProperty.bind(clock.getTimeString());
timeTextField.textProperty().bind(timeStringProperty);
In Clock.java I have:
public StringBinding getTimeString() {
return Bindings.createStringBinding(() -> DateTimeFormatter.ofLocalizedTime(FormatStyle.MEDIUM).format(time.get()), time);
}
where time comes from a TimeLine.
This works well and the current time is displayed and updated in the timeTextfield.
Now I want to add the ability for the user of my program to determine the format of the time e.g. "hh:mm" or "hh:mm:ss".
How can I bind to a formatString, such that the time display updates with the new format as soon as the formatString value is changed?

Answer 1

Introduce an ObjectProperty<DateTimeFormatter> to Clock:
public class Clock {
private final ObjectProperty<DateTimeFormatter> formatter =
new SimpleObjectProperty<>(DateTimeFormatter.ofLocalizedTime(FormatStyle.MEDIUM));
public ObjectProperty<DateTimeFormatter> formatterProperty() {
return formatter ;
}
public final DateTimeFormatter getFormatter() {
return formatterProperty().get();
}
public final void setFormatter(DateTimeFormatter formatter) {
formatterProperty().set(formatter);
}
// ... other code as before
}
And now update the StringBinding so that it uses the formatter and binds to it:
public StringBinding getTimeString() {
return Bindings.createStringBinding(() -> getFormatter().format(time.get()), time, formatter);
}