Java List Uniqne Item unique(List entities)

Description

Gets from a entity list the unique entity expected.

License

Open Source License

Parameter

Parameter	Description
entities	the entity list.

Exception

Parameter	Description
IllegalArgumentException	if it exists more than one entity in the specifiedlist.

Return

the unique entity result.

Declaration

public static <ENTITY> ENTITY unique(List<ENTITY> entities) 

Method Source Code

//package com.java2s;
/**/*from   w w  w .j a v  a  2  s .c o  m*/
 * Copyright (C) 2000 - 2013 Silverpeas
 *
 * This program is free software: you can redistribute it and/or modify it under the terms of the
 * GNU Affero General Public License as published by the Free Software Foundation, either version 3
 * of the License, or (at your option) any later version.
 *
 * As a special exception to the terms and conditions of version 3.0 of the GPL, you may
 * redistribute this Program in connection with Free/Libre Open Source Software ("FLOSS")
 * applications as described in Silverpeas's FLOSS exception. You should have received a copy of the
 * text describing the FLOSS exception, and it is also available here:
 * "http://www.silverpeas.org/docs/core/legal/floss_exception.html"
 *
 * 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
 * Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License along with this program.
 * If not, see <http://www.gnu.org/licenses/>.
 */

import java.util.*;

public class Main {
    /**
     * Gets from a entity list the unique entity expected.
     * @param entities the entity list.
     * @return the unique entity result.
     * @throws IllegalArgumentException if it exists more than one entity in the specified
     * list.
     */
    public static <ENTITY> ENTITY unique(List<ENTITY> entities) {
        if (entities.isEmpty()) {
            return null;
        }
        if (entities.size() == 1) {
            return entities.get(0);
        }
        throw new IllegalArgumentException(
                "wanted to get a unique entity from a list that contains more than one...");
    }
}

Related

1. unique(List array)
2. unique(List list)
3. uniqueList(Collection

   list)

4. uniqueList(List list)
5. uniqueListInsert(List list1, List list2)