/*
 * Copyright (c) 2008, 2009, 2011 Oracle, Inc. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.  The Eclipse Public License is available
 * at http://www.eclipse.org/legal/epl-v10.html and the Eclipse Distribution License
 * is available at http://www.eclipse.org/org/documents/edl-v10.php.
 */
package javax.persistence;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.TYPE;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

Specifies the value of the discriminator column for
entities of the given type.

 The DiscriminatorValue
annotation can only be specified on a concrete entity
class.

 If the DiscriminatorValue annotation is not specified and a discriminator column is used, a provider-specific function will be used to generate a value representing the entity type. If the DiscriminatorType is 
STRING, the discriminator value
default is the entity name.

 The inheritance strategy and the discriminator column
are only specified in the root of an entity class hierarchy
or subhierarchy in which a different inheritance strategy is
applied. The discriminator value, if not defaulted, should be
specified for each entity class in the hierarchy.

   Example:
   @Entity
   @Table(name="CUST")
   @Inheritance(strategy=SINGLE_TABLE)
   @DiscriminatorColumn(name="DISC", discriminatorType=STRING, length=20)
   @DiscriminatorValue("CUSTOMER")
   public class Customer { ... }
   @Entity
   @DiscriminatorValue("VCUSTOMER")
   public class ValuedCustomer extends Customer { ... }

See Also:
DiscriminatorColumn
Since:
Java Persistence 1.0/**
 * Specifies the value of the discriminator column for
 * entities of the given type.
 * <p>
 * <p> The <code>DiscriminatorValue</code>
 * annotation can only be specified on a concrete entity
 * class.
 * <p>
 * <p> If the <code>DiscriminatorValue</code> annotation is not
 * specified and a discriminator column is used, a provider-specific
 * function will be used to generate a value representing the
 * entity type.  If the {@link DiscriminatorType} is <code>
 * STRING</code>, the discriminator value
 * default is the entity name.
 * <p>
 * <p> The inheritance strategy and the discriminator column
 * are only specified in the root of an entity class hierarchy
 * or subhierarchy in which a different inheritance strategy is
 * applied. The discriminator value, if not defaulted, should be
 * specified for each entity class in the hierarchy.
 * <p>
 * <pre>
 *
 *    Example:
 *
 *    &#064;Entity
 *    &#064;Table(name="CUST")
 *    &#064;Inheritance(strategy=SINGLE_TABLE)
 *    &#064;DiscriminatorColumn(name="DISC", discriminatorType=STRING, length=20)
 *    &#064;DiscriminatorValue("CUSTOMER")
 *    public class Customer { ... }
 *
 *    &#064;Entity
 *    &#064;DiscriminatorValue("VCUSTOMER")
 *    public class ValuedCustomer extends Customer { ... }
 * </pre>
 *
 * @see DiscriminatorColumn
 * @since Java Persistence 1.0
 */
@Target({TYPE})
@Retention(RUNTIME)
public @interface DiscriminatorValue {

  
(Optional) The value that indicates that the
row is an entity of the annotated entity type.

 If the DiscriminatorValue annotation is not
specified and a discriminator column is used, a
provider-specific function will be used to generate a value
representing the entity type.  If the DiscriminatorType is
STRING, the discriminator value default is the
entity name.
Returns:
value/**
   * (Optional) The value that indicates that the
   * row is an entity of the annotated entity type.
   * <p>
   * <p> If the <code>DiscriminatorValue</code> annotation is not
   * specified and a discriminator column is used, a
   * provider-specific function will be used to generate a value
   * representing the entity type.  If the <code>DiscriminatorType</code> is
   * <code>STRING</code>, the discriminator value default is the
   * entity name.
   *
   * @return value
   */
  String value();
}