Using like subList() but it take randoms elements. - Java java.util

Java examples for java.util:List Sub List

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Description

Using like subList() but it take randoms elements.

Demo Code

/*//from w w w  .  j a  va2  s.  co m
 * Copyright (C) 2009 - 2012 SMVP4G.COM
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 3 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
//package com.java2s;
import java.util.*;

public class Main {
    public static void main(String[] argv) {
        List list = java.util.Arrays.asList("asdf", "java2s.com");
        int sizeOfSubList = 42;
        randomSubList(list, sizeOfSubList);
    }

    /**
     * Using like subList() but it take randoms elements.
     *
     * @param list
     * @param sizeOfSubList
     */
    public static <E> void randomSubList(List<E> list, int sizeOfSubList) {
        List<E> subList = Collections.emptyList();
        if (isNotEmpty(list) && list.size() > sizeOfSubList) {
            subList = new ArrayList<E>(sizeOfSubList);
            Random generator = new Random();
            for (int i = 0; i < sizeOfSubList; i++) {
                int random = generator.nextInt(list.size());
                subList.add(list.get(random));
                list.remove(random);
            }
        }
        list.clear();
        list.addAll(subList);
    }

    /**
     * Using like isEmpty but it check a collection is not empty or not.
     *
     * @param collection
     * @return false if this collection is null or empty.
     */
    public static boolean isNotEmpty(Collection<?> collection) {
        return !isEmpty(collection);
    }

    /**
     * Check a collection is empty or not.
     *
     * @param collection
     * @return true if this collection is null or empty.
     */
    public static boolean isEmpty(Collection<?> collection) {
        return collection == null || collection.isEmpty();
    }
}

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