Java Random Element randomElement(T... values)

Description

random Element

License

Open Source License

Declaration

public static <T> T randomElement(T... values) 

Method Source Code

//package com.java2s;
/*//from ww  w. j  a  va  2  s  . co  m
 * (c) Copyright 2006-2011 by Volker Bergmann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, is permitted under the terms of the
 * GNU General Public License.
 *
 * For redistributing this software or a derivative work under a license other
 * than the GPL-compatible Free Software License as defined by the Free
 * Software Foundation or approved by OSI, you must first obtain a commercial
 * license to this software product from Volker Bergmann.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED CONDITIONS,
 * REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE
 * HEREBY EXCLUDED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

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

public class Main {
    /** The basic random provider */
    private static Random random = new Random();

    public static <T> T randomElement(T... values) {
        if (values.length == 0)
            throw new IllegalArgumentException("Cannot choose random value from an empty array");
        return values[random.nextInt(values.length)];
    }

    public static <T> T randomElement(List<T> values) {
        return values.get(randomIndex(values));
    }

    public static int randomIndex(List<?> values) {
        if (values.size() == 0)
            throw new IllegalArgumentException("Cannot create random index for an empty array");
        return random.nextInt(values.size());
    }
}

Related

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