https://github.com/javaee/jpa-spec: Java(TM) Persistence API 
Copyright (c) 2008 - 2013 Oracle Corporation. 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.
Contributors:
    Linda DeMichiel - Java Persistence 2.1
    Linda DeMichiel - Java Persistence 2.0

/*******************************************************************************
 * Copyright (c) 2008 - 2013 Oracle Corporation. 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.
 *
 * Contributors:
 *     Linda DeMichiel - Java Persistence 2.1
 *     Linda DeMichiel - Java Persistence 2.0
 *
 ******************************************************************************/ 
package javax.persistence.criteria;

import javax.persistence.metamodel.Attribute;


A join to an entity, embeddable, or basic type.

Type parameters:
  • <Z> – the source type of the join
  • <X> – the target type of the join
Since:Java Persistence 2.0
/**
 * A join to an entity, embeddable, or basic type.
 *
 * @param <Z> the source type of the join
 * @param <X> the target type of the join
 *
 * @since Java Persistence 2.0
 */
public interface Join<Z, X> extends From<Z, X> {

    
 Modify the join to restrict the result according to the
 specified ON condition and return the join object.  
 Replaces the previous ON condition, if any.
 @param restriction  a simple or compound boolean expression
 @return the modified join object
 @since Java Persistence 2.1

/**
     *  Modify the join to restrict the result according to the
     *  specified ON condition and return the join object.  
     *  Replaces the previous ON condition, if any.
     *  @param restriction  a simple or compound boolean expression
     *  @return the modified join object
     *  @since Java Persistence 2.1
     */
    Join<Z, X> on(Expression<Boolean> restriction);

    
 Modify the join to restrict the result according to the
 specified ON condition and return the join object.  
 Replaces the previous ON condition, if any.
 @param restrictions  zero or more restriction predicates
 @return the modified join object
 @since Java Persistence 2.1

/**
     *  Modify the join to restrict the result according to the
     *  specified ON condition and return the join object.  
     *  Replaces the previous ON condition, if any.
     *  @param restrictions  zero or more restriction predicates
     *  @return the modified join object
     *  @since Java Persistence 2.1
     */
    Join<Z, X> on(Predicate... restrictions);

    
 Return the predicate that corresponds to the ON 
 restriction(s) on the join, or null if no ON condition 
 has been specified.
 @return the ON restriction predicate
 @since Java Persistence 2.1

/** 
     *  Return the predicate that corresponds to the ON 
     *  restriction(s) on the join, or null if no ON condition 
     *  has been specified.
     *  @return the ON restriction predicate
     *  @since Java Persistence 2.1
     */
    Predicate getOn();

    
Return the metamodel attribute corresponding to the join.

Returns:metamodel attribute corresponding to the join
/**
     * Return the metamodel attribute corresponding to the join.
     * @return metamodel attribute corresponding to the join
     */
    Attribute<? super Z, ?> getAttribute();

    
Return the parent of the join.

Returns:join parent
/**
     * Return the parent of the join.
     * @return join parent
     */
    From<?, Z> getParent();

    
Return the join type.

Returns:join type
/**
     * Return the join type.
     * @return join type
     */
    JoinType getJoinType();
}