AIR.Common.collections.IGrouping.java Source code

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Here is the source code for AIR.Common.collections.IGrouping.java

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/*******************************************************************************
 * Educational Online Test Delivery System 
 * Copyright (c) 2014 American Institutes for Research
 *   
 * Distributed under the AIR Open Source License, Version 1.0 
 * See accompanying file AIR-License-1_0.txt or at
 * http://www.smarterapp.org/documents/American_Institutes_for_Research_Open_Source_Software_License.pdf
 ******************************************************************************/
/**
 * 
 */
package AIR.Common.collections;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.commons.collections.Transformer;

/**
 * @author Shiva BEHERA [sbehera@air.org]
 * 
 */
public class IGrouping<K, V> extends ArrayList<V> {
    private static final long serialVersionUID = 1L;
    private K _key = null;

    public IGrouping(K key) {
        setKey(key);
    }

    public K getKey() {
        return _key;
    }

    public void setKey(K value) {
        _key = value;
    }

    public static <K, V> List<IGrouping<K, V>> createGroups(Collection<V> list, Transformer transformer) {
        Map<K, IGrouping<K, V>> map = new HashMap<K, IGrouping<K, V>>();
        for (V element : list) {
            @SuppressWarnings("unchecked")
            K groupValue = (K) transformer.transform(element);
            IGrouping<K, V> group = null;
            if (map.containsKey(groupValue)) {
                group = map.get(groupValue);
            } else {
                group = new IGrouping<K, V>(groupValue);
                map.put(groupValue, group);
            }
            group.add(element);
        }
        return new ArrayList<IGrouping<K, V>>(map.values());
    }
}