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/Throwables.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.io.IOException;
import java.io.InterruptedIOException;
import java.io.LineNumberReader;
import java.io.PrintWriter;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * Helps with Throwable objects.
 */
public final class Throwables {

    private Throwables() {
    }

    /**
     * Returns the deepest cause of the given {@code throwable}.
     *
     * @param throwable the throwable to navigate
     * @return the deepest throwable or the given throwable
     */
    public static Throwable getRootCause(final Throwable throwable) {

        // Keep a second pointer that slowly walks the causal chain. If the fast
        // pointer ever catches the slower pointer, then there's a loop.
        Throwable slowPointer = throwable;
        boolean advanceSlowPointer = false;

        Throwable parent = throwable;
        Throwable cause;
        while ((cause = parent.getCause()) != null) {
            parent = cause;
            if (parent == slowPointer) {
                throw new IllegalArgumentException("loop in causal chain");
            }
            if (advanceSlowPointer) {
                slowPointer = slowPointer.getCause();
            }
            advanceSlowPointer = !advanceSlowPointer; // only advance every other iteration
        }
        return parent;

    }

    /**
     * Converts a Throwable stack trace into a List of Strings.
     *
     * @param throwable the Throwable
     * @return a List of Strings
     */
    public static List<String> toStringList(final Throwable throwable) {
        final StringWriter sw = new StringWriter();
        final PrintWriter pw = new PrintWriter(sw);
        try {
            throwable.printStackTrace(pw);
        } catch (final RuntimeException ex) {
            // Ignore any exceptions.
        }
        pw.flush();
        final List<String> lines = new ArrayList<>();
        final LineNumberReader reader = new LineNumberReader(new StringReader(sw.toString()));
        try {
            String line = reader.readLine();
            while (line != null) {
                lines.add(line);
                line = reader.readLine();
            }
        } catch (final IOException ex) {
            if (ex instanceof InterruptedIOException) {
                Thread.currentThread().interrupt();
            }
            lines.add(ex.toString());
        } finally {
            Closer.closeSilently(reader);
        }
        return lines;
    }

    /**
     * Rethrows a {@link Throwable}.
     *
     * @param t the Throwable to throw.
     * @since 2.1
     */
    public static void rethrow(final Throwable t) {
        Throwables.<RuntimeException>rethrow0(t);
    }

    @SuppressWarnings("unchecked")
    private static <T extends Throwable> void rethrow0(final Throwable t) throws T {
        throw (T) t;
    }
}

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

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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