Java List Random Item pickNAtRandom(List vals, int n, long seed)

Description

pick N At Random

License

Open Source License

Declaration

public static <T> List<T> pickNAtRandom(List<T> vals, int n, long seed) 

Method Source Code

//package com.java2s;
/* Soot - a J*va Optimization Framework
 * Copyright (C) 2007 Manu Sridharan/*from   ww w .  j av  a 2  s. c o  m*/
 *
 * This library 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 2.1 of the License, or (at your option) any later version.
 *
 * This library 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 library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

import java.util.ArrayList;

import java.util.HashSet;

import java.util.List;
import java.util.Random;

public class Main {
    public static <T> List<T> pickNAtRandom(List<T> vals, int n, long seed) {
        if (vals.size() <= n) {
            return vals;
        }
        HashSet<T> elems = new HashSet<T>();
        Random rand = new Random(seed);
        for (int i = 0; i < n; i++) {
            boolean added = true;
            do {
                int randIndex = rand.nextInt(n);
                added = elems.add(vals.get(randIndex));
            } while (!added);

        }
        return new ArrayList<T>(elems);
    }
}

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2. newRandomStringList(int size, String... strings)
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4. nextElement(List list)
5. nextRandomElement(final List list)
6. pickOneAtRandom(List list)
7. PickRandom(final Collection list)
8. pickRandom(LinkedList list, int n)
9. pickRandom(List collection)