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- /*
- * Copyright 2000-2014 Vaadin Ltd.
- *
- * 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.
- */
- package com.vaadin.data;
-
- import java.io.Serializable;
- import java.util.ArrayList;
- import java.util.Collections;
- import java.util.List;
-
- import com.vaadin.data.Container.Indexed;
-
- /**
- * Contains helper methods for containers that can be used to ease development
- * of containers in Vaadin.
- *
- * @since 7.0
- */
- public class ContainerHelpers implements Serializable {
-
- /**
- * Get a range of item ids from the container using
- * {@link Indexed#getIdByIndex(int)}. This is just a helper method to aid
- * developers to quickly add the required functionality to a Container
- * during development. This should not be used in a "finished product"
- * unless fetching an id for an index is very inexpensive because a separate
- * request will be performed for each index in the range.
- *
- * @param startIndex
- * index of the first item id to get
- * @param numberOfIds
- * the number of consecutive items whose ids should be returned
- * @param container
- * the container from which the items should be fetched
- * @return A list of item ids in the range specified
- */
- public static List<?> getItemIdsUsingGetIdByIndex(int startIndex,
- int numberOfIds, Container.Indexed container) {
-
- if (container == null) {
- throw new IllegalArgumentException(
- "The given container cannot be null!");
- }
-
- if (startIndex < 0) {
- throw new IndexOutOfBoundsException(
- "Start index cannot be negative! startIndex=" + startIndex);
- }
-
- if (startIndex > container.size()) {
- throw new IndexOutOfBoundsException(
- "Start index exceeds container size! startIndex="
- + startIndex + " containerLastItemIndex="
- + (container.size() - 1));
- }
-
- if (numberOfIds < 1) {
- if (numberOfIds == 0) {
- return Collections.emptyList();
- }
-
- throw new IllegalArgumentException(
- "Cannot get negative amount of items! numberOfItems="
- + numberOfIds);
- }
-
- // not included in the range
- int endIndex = startIndex + numberOfIds;
-
- if (endIndex > container.size()) {
- endIndex = container.size();
- }
-
- ArrayList<Object> rangeOfIds = new ArrayList<Object>();
- for (int i = startIndex; i < endIndex; i++) {
- Object idByIndex = container.getIdByIndex(i);
- if (idByIndex == null) {
- throw new RuntimeException(
- "Unable to get item id for index: "
- + i
- + " from container using Container.Indexed#getIdByIndex() "
- + "even though container.size() > endIndex. "
- + "Returned item id was null. "
- + "Check your container implementation!");
- }
- rangeOfIds.add(idByIndex);
- }
-
- return Collections.unmodifiableList(rangeOfIds);
- }
- }
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