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/*
* Copyright 2000-2016 Vaadin Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.vaadin.event;
import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.EventObject;
import java.util.LinkedHashSet;
import java.util.Set;
/**
* An event that specifies what in a selection has changed, and where the
* selection took place.
*
* @since 7.4
* @author Vaadin Ltd
*/
public class SelectionEvent extends EventObject {
private LinkedHashSet<Object> oldSelection;
private LinkedHashSet<Object> newSelection;
public SelectionEvent(Object source, Collection<Object> oldSelection,
Collection<Object> newSelection) {
super(source);
this.oldSelection = new LinkedHashSet<>(oldSelection);
this.newSelection = new LinkedHashSet<>(newSelection);
}
/**
* A {@link Collection} of all the itemIds that became selected.
* <p>
* <em>Note:</em> this excludes all itemIds that might have been previously
* selected.
*
* @return a Collection of the itemIds that became selected
*/
public Set<Object> getAdded() {
return setDifference(newSelection, oldSelection);
}
/**
* A {@link Collection} of all the itemIds that became deselected.
* <p>
* <em>Note:</em> this excludes all itemIds that might have been previously
* deselected.
*
* @return a Collection of the itemIds that became deselected
*/
public Set<Object> getRemoved() {
return setDifference(oldSelection, newSelection);
}
/**
* Slightly optimized set difference that can return the original set or a
* modified one.
*
* @param set1
* original set
* @param set2
* the set to subtract
* @return the difference set
*/
private static <T> Set<T> setDifference(Set<T> set1, Set<T> set2) {
if (set2.isEmpty()) {
return set1;
} else {
LinkedHashSet<T> set = new LinkedHashSet<>(set1);
set.removeAll(set2);
return set;
}
}
/**
* A {@link Collection} of all the itemIds that are currently selected.
*
* @return a Collection of the itemIds that are currently selected
*/
public Set<Object> getSelected() {
return Collections.unmodifiableSet(newSelection);
}
/**
* The listener interface for receiving {@link SelectionEvent
* SelectionEvents}.
*/
public interface SelectionListener extends Serializable {
/**
* Notifies the listener that the selection state has changed.
*
* @param event
* the selection change event
*/
void select(SelectionEvent event);
}
/**
* The interface for adding and removing listeners for {@link SelectionEvent
* SelectionEvents}.
*/
public interface SelectionNotifier extends Serializable {
/**
* Registers a new selection listener
*
* @param listener
* the listener to register
*/
void addSelectionListener(SelectionListener listener);
/**
* Removes a previously registered selection change listener
*
* @param listener
* the listener to remove
*/
void removeSelectionListener(SelectionListener listener);
}
}
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