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package javafx.collections;

Interface that receives notifications of changes to an ObservableSet.
Type parameters:
<E> – the element type
Since:
JavaFX 2.1/**
 * Interface that receives notifications of changes to an ObservableSet.
 * @param <E> the element type
 * @since JavaFX 2.1
 */
@FunctionalInterface
public interface SetChangeListener<E> {

    
An elementary change done to an ObservableSet.
Change contains information about an add or remove operation.
Note that adding element that is already in the set does not
modify the set and hence no change will be generated.
Type parameters:
<E> – element type
Since:
JavaFX 2.1/**
     * An elementary change done to an ObservableSet.
     * Change contains information about an add or remove operation.
     * Note that adding element that is already in the set does not
     * modify the set and hence no change will be generated.
     *
     * @param <E> element type
     * @since JavaFX 2.1
     */
    public static abstract class Change<E> {

        private ObservableSet<E> set;

        
Constructs a change associated with a set.
Params:
set – the source of the change/**
         * Constructs a change associated with a set.
         * @param set the source of the change
         */
        public Change(ObservableSet<E> set) {
            this.set = set;
        }

        
An observable set that is associated with the change.
Returns:
the source set/**
         * An observable set that is associated with the change.
         * @return the source set
         */
        public ObservableSet<E> getSet() {
            return set;
        }

        
If this change is a result of add operation.
Returns:
true if a new element was added to the set/**
         * If this change is a result of add operation.
         * @return true if a new element was added to the set
         */
        public abstract boolean wasAdded();

        
If this change is a result of removal operation.
Returns:
true if an old element was removed from the set/**
         * If this change is a result of removal operation.
         * @return true if an old element was removed from the set
         */
        public abstract boolean wasRemoved();

        
Get the new element. Return null if this is a removal.
Returns:
the element that was just added/**
         * Get the new element. Return null if this is a removal.
         * @return the element that was just added
         */
        public abstract E getElementAdded();

        
Get the old element. Return null if this is an addition.
Returns:
the element that was just removed/**
         * Get the old element. Return null if this is an addition.
         * @return the element that was just removed
         */
        public abstract E getElementRemoved();

    }

    
Called after a change has been made to an ObservableSet.
This method is called on every elementary change (add/remove) once.
This means, complex changes like removeAll(Collection) or clear()
may result in more than one call of onChanged method.
Params:
change – the change that was made/**
     * Called after a change has been made to an ObservableSet.
     * This method is called on every elementary change (add/remove) once.
     * This means, complex changes like removeAll(Collection) or clear()
     * may result in more than one call of onChanged method.
     *
     * @param change the change that was made
     */
    void onChanged(Change<? extends E> change);
}