com.gemstone.gemfire.cache.query.SelectResults Maven / Gradle / Ivy
/*
* Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you
* may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License. See accompanying
* LICENSE file.
*/
package com.gemstone.gemfire.cache.query;
import java.util.*;
import com.gemstone.gemfire.cache.query.types.*;
/**
* Contains the results of a {@linkplain com.gemstone.gemfire.cache.query.Query#execute() executing} a
* SELECT expression within a query. A SELECT
* expression results in SelectResults that contain instances of
* {@link Struct} if: (a) there is more than one projection in the projection
* attributes, or (b) if the projection is * and there is more than
* one collection specified in the FROM clause.
*
* Otherwise, a SELECT expression over a collection of domain
* objects results in SelectResults that contain domain objects,
* i.e. instances of domain classes such as {@link String} or
* Address.
*
*
* QueryService qs = cacheView.getQueryService();
*
* String select = "SELECT DISTINCT * FROM /root/employees " +
* "WHERE salary > 50000";
* Query query = qs.newQuery(select);
* SelectResults results = query.execute();
*
* for (Iterator iter = results.iterator(); iter.hasNext(); ) {
* Employee emp = (Employee) iter.next();
* System.out.println("Highly compensated: " + emp);
* }
*
* select = "SELECT DISTINCT age, address.zipCode FROM /root/employees " +
* "WHERE salary > 50000";
* query = qs.newQuery(select);
* results = query.execute();
*
* for (Iterator iter = results.iterator(); iter.hasNext(); ) {
* Struct struct = (Struct) iter.next();
* int age = ((Integer) struct.get("age")).intValue();
* String zipCode = (String) struct.get("zipCode");
* System.out.println(age + " -> " + zipCode);
* }
*
*
*
* @see com.gemstone.gemfire.cache.query.Query#execute()
*
* @author Eric Zoerner
* @since 4.0
*/
public interface SelectResults extends Collection {
/**
* Return whether this collection is modifiable. The result of this
* method has no bearing on whether the elements in the collection themselves
* are modifiable.
* @return true if this collection is modifiable, false if not.
*/
public boolean isModifiable();
/**
* Return the number of times element occurs in this collection, that is
* the number of duplicates element has in this collection as defined by
* the equals> method. If element is not present in this
* collection, then 0 is returned.
* @param element the element
* @return the number of occurrances of element
* @since 5.1
*/
public int occurrences(E element);
/**
* Returns this SelectResults as a
* java.util.Set. If this collection is
* distinct and unordered, then no copying is necessary. Otherwise, the
* contents of this collection will be copied into a new instance of
* java.util.HashSet.
* @return Is this collection as a java.util.Set?
*/
public Set asSet();
/**
* Returns this SelectedResults as a
* java.util.List. If this collection is
* ordered, then no copying is necessary. Otherwise, the
* contents of this collection will be copied into a new instance of
* java.util.ArrayList.
* @return this collection as a java.util.List
*/
public List asList();
/** Return the ObjectType for the type of collection this represents.
* @return the CollectionType for the type of collection this represents
*/
public CollectionType getCollectionType();
/**
* Specify a new elementType, overriding any existing known elementType.
* This modifies the CollectionType for this object to be the same collection type
* but with the newly specified element type.
* @param elementType the new elementType
*/
public void setElementType(ObjectType elementType);
}