Source Code for Apache Log4j API

Apache Log4j API provides the interface that applications should code to and provides the adapter components required for implementers to create a logging implementation. Apache Log4j API is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j API is provided in a separate JAR file like log4j-api-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 API 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.util;

import java.util.NoSuchElementException;
import java.util.Stack;

import org.apache.logging.log4j.status.StatusLogger;

 * <em>Consider this class private.</em> Provides various methods to determine the caller class. <h3>Background</h3>
public final class StackLocatorUtil {
    private static StackLocator stackLocator = null;
    private static volatile boolean errorLogged;

    static {
        stackLocator = StackLocator.getInstance();

    private StackLocatorUtil() {

    // TODO: return Object.class instead of null (though it will have a null ClassLoader)
    // (MS) I believe this would work without any modifications elsewhere, but I could be wrong

    // migrated from ReflectiveCallerClassUtility
    public static Class<?> getCallerClass(final int depth) {
        return stackLocator.getCallerClass(depth + 1);

    public static StackTraceElement getStackTraceElement(final int depth) {
        return stackLocator.getStackTraceElement(depth + 1);

    // migrated from ClassLoaderContextSelector
    public static Class<?> getCallerClass(final String fqcn) {
        return getCallerClass(fqcn, Strings.EMPTY);

    // migrated from Log4jLoggerFactory
    public static Class<?> getCallerClass(final String fqcn, final String pkg) {
        return stackLocator.getCallerClass(fqcn, pkg);

    // added for use in LoggerAdapter implementations mainly
    public static Class<?> getCallerClass(final Class<?> anchor) {
        return stackLocator.getCallerClass(anchor);

    // migrated from ThrowableProxy
    public static Stack<Class<?>> getCurrentStackTrace() {
        return stackLocator.getCurrentStackTrace();

    public static StackTraceElement calcLocation(final String fqcnOfLogger) {
        try {
            return stackLocator.calcLocation(fqcnOfLogger);
        } catch (NoSuchElementException ex) {
            if (!errorLogged) {
                errorLogged = true;
                StatusLogger.getLogger().warn("Unable to locate stack trace element for {}", fqcnOfLogger, ex);
            return null;



Or download all of them as a single archive file:

File name: log4j-api-2.14.1-sources.jar
File size: 264773 bytes
Release date: 2021-03-06


Source Code for Apache Log4j Core Implementation

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