Why use JavaFX properties?

Question

Pardon my question if it may seem stupid but I'm curious. I am making a program in Java of which will have a GUI, and am curious about the whole idea of properties. Why use them when we can just add data to a class? For example:

class myButton extends Button {

   private boolean booleanProperty = false;

   myButton(args...) {
      // Do something with the property
   }

   public void setProperty(boolean value) {
      this.booleanProperty = value;
   }

   public boolean getProperty() {
      return this.booleanProperty;
   }
}

Seems to work just fine for storing additional information on the custom implementation of the button. But what about:

class myButton extends Button {

   private SimpleBooleanProperty booleanProperty = new SimpleBooleanProperty(false);

   myButton(args...) {
      // Do something with the property
   }

   public void setProperty(boolean value) {
      this.booleanProperty.set(value);
   }

   public boolean getProperty() {
      return this.booleanProperty.get();
   }
}

The only real difference, I am seeing (correct me if I'm wrong) is that that you can attach listeners to the property values, but I feel as if there has to be more than just that. Ideas?

Answer 1

The power of JavaFX's properties is that they can be bound in ways that will automatically update the UI when a change occurs.

As an example consider an element you want to hide if a textField contains no value:

TextField tf = ...
Node container = ...
container.visibleProperty.bind(tf.textProperty.isNotEmpty());

Now as you change the text in tf, you will see container switching whether its visible based on the presence of text.

Answer 2

They really are useful in a lot of ways I even started them using in non UI related stuff. But look at this example: You habe an undomanager class

public class UndoManager {
    BooleanProperty canUndo = ...;
    BooleanProperty canRedo = ...;

    ...
}

And you have 3 places from where you can invoke undo/redo.

MenuButton menuUndo;
Button toolbarUndo;
MenuButton contextMenuUndo;

You basically only beed to do this:

menuUndo.disabledProperty().bind(undoManager.undoProperty()):
toolbarUndo.disabledProperty().bind(undoManager.undoProperty());
contextMenuUndo.disabledProperty().bind(undoManager.undoProperty());

and you dont ever have to worry about it again. If you add a new place where an undo can happen you just have to bind it too.