EntityBase.java

/*
 * Copyright (c) 2011, Municipiality of Vienna, Austria
 *
 * Licensed under the EUPL, Version 1.1 or � as soon they
 * will be approved by the European Commission - subsequent
 * versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the
 * Licence.
 * 
 * For convenience a plain text copy of the English version 
 * of the Licence can be found in the file LICENCE.txt in
 * the top-level directory of this software distribution.
 * 
 * You may obtain a copy of the Licence in any of 22 European
 * Languages at:
 *
 * http://www.osor.eu/eupl
 *
 * Unless required by applicable law or agreed to in
 * writing, software distributed under the Licence is
 * distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied.
 * See the Licence for the specific language governing
 * permissions and limitations under the Licence.
 */

package org.azzyzt.jee.runtime.entity;

/**
 * Abstract base class for all entity classes. Inheriting from this class guarantees availability 
 * of an ID value. Additionally static and non-static tests for ID values are included. 
 *
 * @param <ID> the type of the entity class' ID
 */
public abstract class EntityBase<ID> {

	/**
	 * @param id a value to be tested
	 * @return true if the value of the parameter could possibly an ID value.
	 */
	public static boolean couldBeIdValue(Object id) {
		
		if (id == null) return false;
		
		if (id instanceof Number) {
			long longId = ((Number)id).longValue();
			return longId > 0L; // we may need to relax this to "longId != 0L" for some databases
		} else {
			return true;
		}
	}

	/**
	 * @return true if an entity is likely to have a valid ID value
	 */
	public boolean likelyHasId() {
		return couldBeIdValue(getId());
	}

	/**
	 * @return the ID of an entity
	 */
	public abstract ID getId();

	/**
	 * Sets the ID of an entity to a certain value.
	 * 
	 * @param id a value
	 */
	public abstract void setId(ID id);
}