Java Random Element randomElementOf(final List list)

Description

Get a random element from the list.

License

Open Source License

Parameter

Parameter	Description
list	the input list
T	the type of elements in the list

Return

a random element from the list or null if the list is empty

Declaration

public static <T> T randomElementOf(final List<T> list) 

Method Source Code

//package com.java2s;
/**//w w w  .j  ava2s.com
 * The MIT License
 *
 *   Copyright (c) 2016, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)
 *
 *   Permission is hereby granted, free of charge, to any person obtaining a copy
 *   of this software and associated documentation files (the "Software"), to deal
 *   in the Software without restriction, including without limitation the rights
 *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *   copies of the Software, and to permit persons to whom the Software is
 *   furnished to do so, subject to the following conditions:
 *
 *   The above copyright notice and this permission notice shall be included in
 *   all copies or substantial portions of the Software.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *   THE SOFTWARE.
 */

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

public class Main {
    /**
     * Get a random element from the list.
     *
     * @param list the input list
     * @param <T>  the type of elements in the list
     * @return a random element from the list or null if the list is empty
     */
    public static <T> T randomElementOf(final List<T> list) {
        if (list.isEmpty()) {
            return null;
        }
        return list.get(nextInt(0, list.size()));
    }

    private static int nextInt(int startInclusive, int endExclusive) {
        return startInclusive + new Random().nextInt(endExclusive - startInclusive);
    }
}

Related

1. randomElement(final Set set)
2. randomElement(int[] anArray)
3. randomElement(List list)
4. randomElement(T... values)
5. randomElement(T[] array)
6. randomElementOf(String[] array)
7. randomEles(List list, int count)