org.opencastproject.util.SmartIterator Maven / Gradle / Ivy
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* Licensed to The Apereo Foundation under one or more contributor license
* agreements. See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
*
*
* The Apereo Foundation licenses this file to you under the Educational
* Community 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://opensource.org/licenses/ecl2.txt
*
* 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 org.opencastproject.util;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
/**
* Utility class for applying limit and offset to a map or collection
*/
public class SmartIterator {
private int limit;
private int offset;
private Iterator iterator;
public SmartIterator(int limit, int offset) {
this.limit = limit;
this.offset = offset;
}
/**
* Apply limit and offset to a map of value type {@link A}
*
* @param map
* the map
* @return the filtered map
*/
public Map applyLimitAndOffset(Map map) {
iterator = map.entrySet().iterator();
Map filteredMap = new LinkedHashMap();
int i = 0;
while (isRecordRequired(filteredMap.size())) {
Entry item = (Entry) iterator.next();
if (i++ >= offset) {
filteredMap.put(item.getKey(), item.getValue());
}
}
return filteredMap;
}
private boolean isRecordRequired(int filteredMapSize) {
return (filteredMapSize < limit || limit == 0) && iterator.hasNext();
}
/**
* Apply limit and offset to a collection of type {@link A}
*
* @param unfilteredCollection
* the collection
* @return the filtered list
*/
public List applyLimitAndOffset(Collection unfilteredCollection) {
iterator = unfilteredCollection.iterator();
List filteredList = new ArrayList();
int i = 0;
while (isRecordRequired(filteredList.size())) {
A nextItem = (A) iterator.next();
if (i++ >= offset) {
filteredList.add(nextItem);
}
}
return filteredList;
}
}