EDIT

package eu.etaxonomy.taxeditor.store.model;

import org.eclipse.swt.dnd.ByteArrayTransfer;

import org.eclipse.swt.dnd.TransferData;

import eu.etaxonomy.cdm.model.taxon.TaxonBase;

/**

 * For drag and drop - a drag widget with this transfer type can only be dropped onto

 *  a drop widget with the same type.

 *    

 * @author p.ciardelli

 *

 */

public class TaxonTransfer extends ByteArrayTransfer {

	private static final String TAXONTYPENAME = "taxon_type";

	private static final int TAXONTYPEID = registerType (TAXONTYPENAME);		

	private static final TaxonTransfer INSTANCE = new TaxonTransfer();

	/*

	 * The object associated with this transfer event

	 */

	private TaxonBase taxonBase;

	/*

	 * Returns the singleton

	 */

	public static TaxonTransfer getInstance() {

		return INSTANCE;

	}

	/*

	 * Set transfer data for local use

	 */

	public void setTaxon(TaxonBase taxon) {

		this.taxonBase = taxon;

	}

	/*

	 * Returns the local transfer data

	 */

	public TaxonBase getTaxon() {

		return taxonBase;

	}

	/* 

	 * The type ID is used to identify this transfer

	 */

	@Override

	protected int[] getTypeIds() {

		return new int[] { TAXONTYPEID };

	}

	@Override

	protected String[] getTypeNames() {

		return new String[] { TAXONTYPENAME } ;

	}

	@Override

	protected void javaToNative(Object object, TransferData transferData) {

		// No encoding needed since this is a hardcoded string read and written

		// in the same process.

		// See nativeToJava below

		byte[] check = TAXONTYPENAME.getBytes();

		super.javaToNative(check, transferData);

	}

	@Override

	protected Object nativeToJava(TransferData transferData) {

		Object result = super.nativeToJava(transferData);

		if (isInvalidNativeType(result)) {

			throw new RuntimeException(); //$NON-NLS-1$

		}

		return taxonBase;

	}

	private boolean isInvalidNativeType(Object result) {

		// No encoding needed since this is a hardcoded string read and written

		// in the same process.

		// See javaToNative above

		return !(result instanceof byte[])

				|| !TAXONTYPENAME.equals(new String((byte[]) result));

	}

}