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.TupleElement;
import java.util.List;


The Selection interface defines an item that is to be
returned in a query result.

Type parameters:
  • <X> – the type of the selection item
Since:Java Persistence 2.0
/**
 * The <code>Selection</code> interface defines an item that is to be
 * returned in a query result.
 *
 * @param <X> the type of the selection item
 *
 * @since Java Persistence 2.0
 */
public interface Selection<X> extends TupleElement<X> {

    
Assigns an alias to the selection item.
Once assigned, an alias cannot be changed or reassigned.
Returns the same selection item.

Params:
  • name –  alias
Returns:selection item
/**
     * Assigns an alias to the selection item.
     * Once assigned, an alias cannot be changed or reassigned.
     * Returns the same selection item.
     * @param name  alias
     * @return selection item 
     */
    Selection<X> alias(String name);

    
Whether the selection item is a compound selection.

Returns:boolean indicating whether the selection is a compound
        selection
/**
     * Whether the selection item is a compound selection.
     * @return boolean indicating whether the selection is a compound
     *         selection
     */
    boolean isCompoundSelection();

    
Return the selection items composing a compound selection.
Modifications to the list do not affect the query.

Throws:
Returns:list of selection items
/**
     * Return the selection items composing a compound selection.
     * Modifications to the list do not affect the query.
     * @return list of selection items
     * @throws IllegalStateException if selection is not a 
     *         compound selection
     */
    List<Selection<?>> getCompoundSelectionItems();
}