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 java.util.Collection;


Type for query expressions.

Type parameters:
  • <T> – the type of the expression
Since:Java Persistence 2.0
/**
 * Type for query expressions.
 *
 * @param <T> the type of the expression
 *
 * @since Java Persistence 2.0
 */
public interface Expression<T> extends Selection<T> {

    
 Create a predicate to test whether the expression is null.
 @return predicate testing whether the expression is null

/**
     *  Create a predicate to test whether the expression is null.
     *  @return predicate testing whether the expression is null
     */
    Predicate isNull();

    
 Create a predicate to test whether the expression is 
 not null.
 @return predicate testing whether the expression is not null

/**
     *  Create a predicate to test whether the expression is 
     *  not null.
     *  @return predicate testing whether the expression is not null
     */
    Predicate isNotNull();

    
Create a predicate to test whether the expression is a member
of the argument list.

Params:
  • values –  values to be tested against
Returns:predicate testing for membership
/**
     * Create a predicate to test whether the expression is a member
     * of the argument list.
     * @param values  values to be tested against
     * @return predicate testing for membership
     */
    Predicate in(Object... values);

    
Create a predicate to test whether the expression is a member
of the argument list.

Params:
  • values –  expressions to be tested against
Returns:predicate testing for membership
/**
     * Create a predicate to test whether the expression is a member
     * of the argument list.
     * @param values  expressions to be tested against
     * @return predicate testing for membership
     */
    Predicate in(Expression<?>... values);

    
Create a predicate to test whether the expression is a member
of the collection.

Params:
  • values –  collection of values to be tested against
Returns:predicate testing for membership
/**
     * Create a predicate to test whether the expression is a member
     * of the collection.
     * @param values  collection of values to be tested against
     * @return predicate testing for membership
     */
    Predicate in(Collection<?> values);

    
Create a predicate to test whether the expression is a member
of the collection.

Params:
  • values – expression corresponding to collection to be
       tested against
Returns:predicate testing for membership
/**
     * Create a predicate to test whether the expression is a member
     * of the collection.
     * @param values expression corresponding to collection to be
     *        tested against
     * @return predicate testing for membership
     */
    Predicate in(Expression<Collection<?>> values);

    
Perform a typecast upon the expression, returning a new
expression object.
This method does not cause type conversion:
the runtime type is not changed.
Warning: may result in a runtime failure.

Params:
  • type –  intended type of the expression
Returns:new expression of the given type
/**
     * Perform a typecast upon the expression, returning a new
     * expression object.
     * This method does not cause type conversion:
     * the runtime type is not changed.
     * Warning: may result in a runtime failure.
     * @param type  intended type of the expression
     * @return new expression of the given type
     */
    <X> Expression<X> as(Class<X> type);
}