JavaFX binding and property change

Question

I'm working in JavaFX with bindings and properties. I have a Label label and a Person currentPerson . I have the following code:

label.textProperty().bind(currentPerson.nameProperty());

Then I have in another section of code:

currentPerson = newPerson;   //newPerson is a given Person instance

This way the textProperty of label doesn't update!

But if I do in that section of code:

currentPerson.setName(newPerson.getName());

then this updates the textProperty of label .

My question is: why does the second way update the textProperty of label , while the first doesn't, even though the nameProperty of currentPerson is changed in both cases?

Answer 1

I think the most basic answer to your question is that, after the line currentPerson = newPerson; , the currentPerson object is not the same object that was bound to label previously.

Answer 2

As mentioned , You've lost your first binding after :

currentPerson = newPerson;

The solution is either (re)bind currentPerson after any assignment to currentPerson , or instead, use a method to pass the newPerson data, like:

currentPerson.setPerson(newPerson);


public class Person{

    private StringProperty name = new SimpleStringProperty();

    // ....


    public void setPerson(Person person) {
        // ....
        this.name.set(person.name.get());
    }
}

Answer 3

您必须设置bind该person's name相关的bind ，因此当您使用getName ，它会更新label