ListSelectionMaintainer.java

package org.obo.app.swing;

import javax.swing.SwingUtilities;

import org.apache.log4j.Logger;

import ca.odell.glazedlists.EventList;
import ca.odell.glazedlists.event.ListEvent;
import ca.odell.glazedlists.event.ListEventListener;
import ca.odell.glazedlists.swing.EventSelectionModel;

/**
 * This class listens to changes to an EventList and its associated EventSelectionModel. 
 * It attempts to prevent an empty selection in the selection model, by selecting the next 
 * item after one is deleted, and selecting newly inserted items. 
 * 
 * @author Jim Balhoff
 */
public class ListSelectionMaintainer<T> {

	private final EventList<T> list;
	private final EventSelectionModel<T> selectionModel;

	public ListSelectionMaintainer(EventList<T> list, EventSelectionModel<T> selectionModel) {
		this.list = list;
		this.selectionModel = selectionModel;
		this.list.addListEventListener(new ListListener<T>());
	}

	private void selectIndex(int index) {
		if (index < this.list.size()) {
			selectionModel.setSelectionInterval(index, index);
		}
	}

	private class ListListener<E> implements ListEventListener<E> {

		@Override
		public void listChanged(final ListEvent<E> listChanges) {
			int index = -1;
			while (listChanges.hasNext()) {
				listChanges.next();
				if ((listChanges.getType() == ListEvent.UPDATE) || (listChanges.isReordering())) {
					return;
				}
				index = listChanges.getIndex();
			}
			final int selectionIndex = (index > (list.size() - 1)) ? (list.size() - 1) : index;
			if (selectionIndex > -1) {
				// must use invokeLater because the selection model will not have found out about the inserted item yet
				SwingUtilities.invokeLater(new Runnable() {
					@Override
					public void run() {
						selectIndex(selectionIndex);
					}
				});
			}
		}

	}

	@SuppressWarnings("unused")
	private Logger log() {
		return Logger.getLogger(this.getClass());
	}

}