Collections and Concurrency - JavaFX 8: A Definitive Guide to Building Desktop, Mobile, and Embedded Java Clients - page 283

boolean wasAdded() returns true if a new element was added to the set. •

boolean wasRemoved() returns true if an element was removed from the set. •

E getElementAdded() returns the element that was added to the set.

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E getElementRemoved() returns the element that was removed from the set. •

ObservableSet<E> getSet()
In the example in Listing 7-4, we perform various set manipulations after attaching a SetChangeListener to
an ObservableSet . The implementation of SetChangeListener , called MyListener , includes a pretty printer for the
SetChangeListener.Change object, and prints out the set change event object when an event is fired.

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Listing 7-4. SetChangeEventExample.java
import javafx.collections.FXCollections;
import javafx.collections.ObservableSet;
import javafx.collections.SetChangeListener;

import java.util.Arrays;

public class SetChangeEventExample {
public static void main(String[] args) {
ObservableSet<String> set = FXCollections.observableSet();
set.addListener(new MyListener());

System.out.println("Calling add(\"First\"): ");
set.add("First");

System.out.println("Calling addAll(Arrays.asList(\"Second\", \"Third\")): ");
set.addAll(Arrays.asList("Second", "Third"));

System.out.println("Calling remove(\"Third\"): ");
set.remove("Third");
}

private static class MyListener implements SetChangeListener<String> {
@Override
public void onChanged(Change<? extends String> change) {
System.out.println("\tset = " + change.getSet());
System.out.println(prettyPrint(change));
}

private String prettyPrint(Change<? extends String> change) {
StringBuilder sb = new StringBuilder("\tChange event data:\n");
sb.append("\t\tWas added: ").append(change.wasAdded()).append("\n");
sb.append("\t\tWas removed: ").append(change.wasRemoved()).append("\n");
sb.append("\t\tElement added: ").append(change.getElementAdded()).append("\n");
sb.append("\t\tElement removed: ").append(change.getElementRemoved()).append("\n");
return sb.toString();
}
}
}