org.jeasy.random.randomizers.misc.EnumRandomizer Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of easy-random-core Show documentation
Easy Random core implementation
The newest version!
/*
 * The MIT License
 *
 *   Copyright (c) 2020, Mahmoud Ben Hassine ([email protected])
 *
 *   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.
 */
package org.jeasy.random.randomizers.misc;

import org.jeasy.random.api.Randomizer;
import org.jeasy.random.randomizers.AbstractRandomizer;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

/**
 * A {@link Randomizer} that generates a random value from a given {@link Enum}.
 *
 * @param  the type of elements in the enumeration
 * @author Mahmoud Ben Hassine ([email protected])
 */
public class EnumRandomizer> extends AbstractRandomizer {

    private List enumConstants;

    /**
     * Create a new {@link EnumRandomizer}.
     *
     * @param enumeration the enumeration from which this randomizer will generate random values
     */
    public EnumRandomizer(final Class enumeration) {
        super();
        this.enumConstants = Arrays.asList(enumeration.getEnumConstants());
    }

    /**
     * Create a new {@link EnumRandomizer}.
     *
     * @param enumeration the enumeration from which this randomizer will generate random values
     * @param seed        the initial seed
     */
    public EnumRandomizer(final Class enumeration, final long seed) {
        super(seed);
        this.enumConstants = Arrays.asList(enumeration.getEnumConstants());
    }

    /**
     * Create a new {@link EnumRandomizer}.
     *
     * @param enumeration    the enumeration from which this randomizer will generate random values
     * @param excludedValues the values to exclude from random picking
     * @throws IllegalArgumentException when excludedValues contains all enumeration values,
     *                                  ie all elements from the enumeration are excluded
     */
    public EnumRandomizer(final Class enumeration, final E... excludedValues) throws IllegalArgumentException {
        checkExcludedValues(enumeration, excludedValues);
        this.enumConstants = getFilteredList(enumeration, excludedValues);
    }

    /**
     * Get a random value within an enumeration or an enumeration subset (when values are excluded)
     *
     * @return a random value within the enumeration
     */
    @Override
    public E getRandomValue() {
        if (enumConstants.isEmpty()) {
            return null;
        }
        int randomIndex = random.nextInt(enumConstants.size());
        return enumConstants.get(randomIndex);
    }

    private void checkExcludedValues(Class enumeration, E[] excludedValues) {
        boolean excludedValuesIncludeAllValues = Arrays.asList(excludedValues).containsAll(Arrays.asList(enumeration.getEnumConstants()));
        if (excludedValuesIncludeAllValues) {
            throw new IllegalArgumentException("No enum element available for random picking.");
        }
    }

    /**
     * Get a subset of enumeration.
     *
     * @return the enumeration values minus those excluded.
     */
    private List getFilteredList(Class enumeration, E... excludedValues) {
        List filteredValues = new ArrayList<>();
        Collections.addAll(filteredValues, enumeration.getEnumConstants());
        if (excludedValues != null) {
            for (E element : excludedValues) {
                filteredValues.remove(element);
            }
        }
        return filteredValues;
    }
}