Source Code for Apache Log4j Core Implementation

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 and source package like You can download them at Apache Log4j Website.

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



 * 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
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the license for the specific language governing permissions and
 * limitations under the license.
package org.apache.logging.log4j.core.config;

import java.util.Comparator;
import java.util.Objects;

 * Comparator for classes annotated with {@link Order}.
 * @since 2.1
public class OrderComparator implements Comparator<Class<?>>, Serializable {

    private static final long serialVersionUID = 1L;
    private static final Comparator<Class<?>> INSTANCE = new OrderComparator();

     * Returns a singleton instance of this class.
     * @return the singleton for this class.
    public static Comparator<Class<?>> getInstance() {
        return INSTANCE;

    public int compare(final Class<?> lhs, final Class<?> rhs) {
        final Order lhsOrder = Objects.requireNonNull(lhs, "lhs").getAnnotation(Order.class);
        final Order rhsOrder = Objects.requireNonNull(rhs, "rhs").getAnnotation(Order.class);
        if (lhsOrder == null && rhsOrder == null) {
            // both unannotated means equal priority
            return 0;
        // if only one class is @Order-annotated, then prefer that one
        if (rhsOrder == null) {
            return -1;
        if (lhsOrder == null) {
            return 1;
        // larger value means higher priority
        return Integer.signum(rhsOrder.value() - lhsOrder.value());



Or download all of them as a single archive file:

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


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