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Efficient reliable UDP unicast, UDP multicast, and IPC transport protocol.
There is a newer version: 1.46.2
/*
 * Copyright 2014-2023 Real Logic Limited.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.aeron.archive.checksum;

import java.util.Objects;

/**
 * Factory and common methods for working with {@link Checksum} instances.
 */
public final class Checksums
{
    /**
     * Returns an instance of {@link Checksum} that computes CRC-32 checksums.
     *
     * @return CRC-32 implementation.
     */
    public static Checksum crc32()
    {
        return Crc32.INSTANCE;
    }

    /**
     * Returns an instance of {@link Checksum} that computes CRC-32C checksums.
     *
     * @return CRC-32C implementation.
     * @throws IllegalStateException if invoked on a JDK 8.
     */
    public static Checksum crc32c()
    {
        if (null == Crc32c.INSTANCE)
        {
            throw new IllegalStateException("CRC-32C is not available on the current JDK!");
        }

        return Crc32c.INSTANCE;
    }

    /**
     * Factory method to create an instance of the {@link Checksum} interface.
     *
     * @param className fully qualified class name of the {@link Checksum} implementation.
     * @return a {@link Checksum} instance.
     * @throws NullPointerException     if {@code className == null}.
     * @throws IllegalStateException    if an attempt was made to acquire CRC-32C while running on JDK 8.
     * @throws IllegalArgumentException if an error occurs while creating a {@link Checksum} instance.
     * @throws ClassCastException       if created instance does not implement the {@link Checksum} interface.
     * @see #crc32c()
     */
    public static Checksum newInstance(final String className)
    {
        Objects.requireNonNull(className, "className is required!");

        if (Crc32.class.getName().equals(className))
        {
            return crc32();
        }
        else if (Crc32c.class.getName().equals(className))
        {
            return crc32c();
        }
        else
        {
            try
            {
                final Class klass = Class.forName(className);
                final Object instance = klass.getDeclaredConstructor().newInstance();
                return (Checksum)instance;
            }
            catch (final ReflectiveOperationException ex)
            {
                throw new IllegalArgumentException("failed to create Checksum instance for class: " + className, ex);
            }
        }
    }
}