EDIT

/**

 * 

 */

package eu.etaxonomy.taxeditor.navigation.key.polytomous;

import java.util.Collections;

import java.util.Comparator;

import java.util.List;

import org.eclipse.jface.viewers.IStructuredContentProvider;

import org.eclipse.jface.viewers.Viewer;

/**

 * @author n.hoffmann

 *

 */

public class PolytomousKeyContentProvider implements IStructuredContentProvider{

	@Override

	public void dispose() {

	}

	@Override

	public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {

	}

	@Override

	public Object[] getElements(Object inputElement) {

		if(inputElement instanceof List){

			Collections.sort((List)inputElement,new PolytomousKeyComparator());

			return ((List) inputElement).toArray();

		}

		return null;

	}

	public class PolytomousKeyComparator implements Comparator<Object> {

		@Override

		public int compare(Object o1, Object o2) {

			if(o1 == null && o2 == null) {

				return 0;

			} else if (o1 == null) {

				return -1;

			} else if(o2 == null) {

				return +1;

			} else {

				return o1.toString().compareTo(o2.toString());

			}

		}

	}

}