org.orcas.commons.collections.CollectionUtils.java Source code

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Here is the source code for org.orcas.commons.collections.CollectionUtils.java

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/**
 * Copyright (C) 2010  Marcellus C. Tavares
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
    
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
    
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.orcas.commons.collections;

import org.apache.commons.collections.Bag;
import org.orcas.commons.collections.bag.HashBag;
import org.orcas.commons.collections.list.TreeList;
import org.orcas.commons.collections.set.HashSet;

import java.util.Collection;
import java.util.Iterator;
import java.util.Set;

@SuppressWarnings("unchecked")
public class CollectionUtils extends org.apache.commons.collections.CollectionUtils {

    public static <E> E at(Collection<E> collection, int index) throws Exception {

        Iterator<E> itr = collection.iterator();

        for (int i = 0; itr.hasNext(); i++) {
            E element = itr.next();

            if (i == index) {
                return element;
            }
        }

        return null;
    }

    public static <E> Collection<E> excluding(Collection<E> collection, E object) throws Exception {

        collection.remove(object);

        return collection;
    }

    public static <E> Collection<E> including(Collection<E> collection, E object) throws Exception {

        collection.add(object);

        return collection;
    }

    public static <E> Collection<E> reject(Collection<E> collection, String iteratorName, String expression)
            throws Exception {

        Collection<E> selected = select(collection, iteratorName, expression);

        collection.removeAll(selected);

        return collection;
    }

    public static <E> Collection<E> select(Collection<E> collection, String iteratorName, String expression)
            throws Exception {

        if (collection.isEmpty()) {
            return collection;
        }

        Collection<E> result = _createBasedOnType(collection);

        for (Iterator<E> it = collection.iterator(); it.hasNext();) {
            E object = it.next();

            if (EvaluatorUtil.evaluate(object, iteratorName, expression)) {
                result.add(object);
            }
        }

        return result;
    }

    private static <E> Collection<E> _createBasedOnType(Collection<E> collection) {

        if (collection instanceof Bag) {
            return new HashBag<E>();
        } else if (collection instanceof Set) {
            return new HashSet<E>();
        } else {
            return new TreeList<E>();
        }
    }

}