Apache Log4j Core Implementation provides the functional components of the logging system. Users are free to create their own plugins and include them in the logging configuration. Apache Log4j Core is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j Core Implementation is provided in a separate JAR file like log4j-core-2.14.1.jar.

Source Code files for Apache Log4j API are provided in both binary packge like apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j Core Implementation 2.14.1 below.

⏎ org/apache/logging/log4j/core/util/ArrayUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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
 *
 *      http://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 org.apache.logging.log4j.core.util;

import java.lang.reflect.Array;

/**
 * Copied from Apache Commons Lang (including the {@code @since} tags.)
 */
public class ArrayUtils {

    /**
     * Checks if an array of Objects is empty or {@code null}.
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final byte[] array) {
        return getLength(array) == 0;
    }
    
    /**
     * <p>Returns the length of the specified array.
     * This method can deal with {@code Object} arrays and with primitive arrays.</p>
     *
     * <p>If the input array is {@code null}, {@code 0} is returned.</p>
     *
     * <pre>
     * ArrayUtils.getLength(null)            = 0
     * ArrayUtils.getLength([])              = 0
     * ArrayUtils.getLength([null])          = 1
     * ArrayUtils.getLength([true, false])   = 2
     * ArrayUtils.getLength([1, 2, 3])       = 3
     * ArrayUtils.getLength(["a", "b", "c"]) = 3
     * </pre>
     *
     * @param array  the array to retrieve the length from, may be null
     * @return The length of the array, or {@code 0} if the array is {@code null}
     * @throws IllegalArgumentException if the object argument is not an array.
     * @since 2.1
     */
    public static int getLength(final Object array) {
        if (array == null) {
            return 0;
        }
        return Array.getLength(array);
    }

    /**
     * <p>Removes the element at the specified position from the specified array.
     * All subsequent elements are shifted to the left (subtracts one from
     * their indices).</p>
     *
     * <p>This method returns a new array with the same elements of the input
     * array except the element on the specified position. The component
     * type of the returned array is always the same as that of the input
     * array.</p>
     *
     * <p>If the input array is {@code null}, an IndexOutOfBoundsException
     * will be thrown, because in that case no valid index can be specified.</p>
     *
     * @param array  the array to remove the element from, may not be {@code null}
     * @param index  the position of the element to be removed
     * @return A new array containing the existing elements except the element
     *         at the specified position.
     * @throws IndexOutOfBoundsException if the index is out of range
     * (index &lt; 0 || index &gt;= array.length), or if the array is {@code null}.
     * @since 2.1
     */
    private static Object remove(final Object array, final int index) {
        final int length = getLength(array);
        if (index < 0 || index >= length) {
            throw new IndexOutOfBoundsException("Index: " + index + ", Length: " + length);
        }

        final Object result = Array.newInstance(array.getClass().getComponentType(), length - 1);
        System.arraycopy(array, 0, result, 0, index);
        if (index < length - 1) {
            System.arraycopy(array, index + 1, result, index, length - index - 1);
        }

        return result;
    }

    /**
     * <p>Removes the element at the specified position from the specified array.
     * All subsequent elements are shifted to the left (subtracts one from
     * their indices).</p>
     *
     * <p>This method returns a new array with the same elements of the input
     * array except the element on the specified position. The component
     * type of the returned array is always the same as that of the input
     * array.</p>
     *
     * <p>If the input array is {@code null}, an IndexOutOfBoundsException
     * will be thrown, because in that case no valid index can be specified.</p>
     *
     * <pre>
     * ArrayUtils.remove(["a"], 0)           = []
     * ArrayUtils.remove(["a", "b"], 0)      = ["b"]
     * ArrayUtils.remove(["a", "b"], 1)      = ["a"]
     * ArrayUtils.remove(["a", "b", "c"], 1) = ["a", "c"]
     * </pre>
     *
     * @param <T> the component type of the array
     * @param array  the array to remove the element from, may not be {@code null}
     * @param index  the position of the element to be removed
     * @return A new array containing the existing elements except the element
     *         at the specified position.
     * @throws IndexOutOfBoundsException if the index is out of range
     * (index &lt; 0 || index &gt;= array.length), or if the array is {@code null}.
     * @since 2.1
     */
    @SuppressWarnings("unchecked") // remove() always creates an array of the same type as its input
    public static <T> T[] remove(final T[] array, final int index) {
        return (T[]) remove((Object) array, index);
    }

}

⏎ org/apache/logging/log4j/core/util/ArrayUtils.java

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File name: log4j-core-2.14.1-sources.jar
File size: 1281358 bytes
Release date: 2021-03-06
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