JavaFX，ObservableList：如何在列表对象被修改时激发InvalidationListener？

Question

public class SomeObservableClass{

  private StringProperty prop1 = new SimpleStringProperty();
  private DoubleProperty prop2 = new SimpleDoubleProperty();

  ... constructors, getters and setters
}

public class ParentClass{
  private ObservableList<SomeObservableClass> sOC = FXCollections.observableArrayList();`
}

public class ParentClass{
  private ObservableList<SomeObservableClass> observableList = FXCollections.observableArrayList();

  public`ParentClass(List<SomeObservableClass> list){
    this.observableList.addAll(list);
    this.observableList.addListener((InvalidationListener) observable -> System.out.println("listener detected a change!"));`.
  }
}

public class Controller(){
  private ParentClass parentClass;

  public void changeSomeProps(){
    SomeObservableClass anObservableObject = parentClass.getObservableList().get(0);
    anObservableObject.setProp1("newVal");
  }
}

我怀疑我缺少一些代码来让侦听器知道当列表对象的任何属性被修改时它应该触发，但我不知道如何做到这一点。

Answer 1

默认情况下，ObservableList不处理项内容的更改。但是用提取器实例化ObservableList可以处理它们。

ObservableList<SomeObservableClass> observableList = FXCollections.observableArrayList(
            e -> new Observable[]{e.prop1Property(), e.prop2Property()});

// add items and set listeners here

observableList.get(1).setProp1("newVal");
// It fires InvalidationListener and ListChangeListener.

编辑：

似乎只有ListChangeListener才能识别更新的项。请试试看。

observableList.addListener((ListChangeListener) change -> {
    while (change.next()) {
        if (change.wasUpdated()) {
            SomeObservableClass changedItem = observableList.get(change.getFrom());
            System.out.println("ListChangeListener item: " + changedItem);
        }
    }
});