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/Assert.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.util.Collection;
import java.util.Map;

/**
 * Utility class providing common validation logic.
 */
public final class Assert {
    private Assert() {
    }

    /**
     * Checks if an object has empty semantics. The following scenarios are considered empty:
     * <ul>
     * <li>{@code null}</li>
     * <li>empty {@link CharSequence}</li>
     * <li>empty array</li>
     * <li>empty {@link Iterable}</li>
     * <li>empty {@link Map}</li>
     * </ul>
     *
     * @param o value to check for emptiness
     * @return true if the value is empty, false otherwise
     * @since 2.8
     */
    public static boolean isEmpty(final Object o) {
        if (o == null) {
            return true;
        }
        if (o instanceof CharSequence) {
            return ((CharSequence) o).length() == 0;
        }
        if (o.getClass().isArray()) {
            return ((Object[]) o).length == 0;
        }
        if (o instanceof Collection) {
            return ((Collection<?>) o).isEmpty();
        }
        if (o instanceof Map) {
            return ((Map<?, ?>) o).isEmpty();
        }
        return false;
    }

    /**
     * Opposite of {@link #isEmpty(Object)}.
     *
     * @param o value to check for non-emptiness
     * @return true if the value is non-empty, false otherwise
     * @since 2.8
     */
    public static boolean isNonEmpty(final Object o) {
        return !isEmpty(o);
    }

    /**
     * Checks a value for emptiness and throws an IllegalArgumentException if it's empty.
     *
     * @param value value to check for emptiness
     * @param <T>   type of value
     * @return the provided value if non-empty
     * @since 2.8
     */
    public static <T> T requireNonEmpty(final T value) {
        return requireNonEmpty(value, "");
    }

    /**
     * Checks a value for emptiness and throws an IllegalArgumentException if it's empty.
     *
     * @param value   value to check for emptiness
     * @param message message to provide in exception
     * @param <T>     type of value
     * @return the provided value if non-empty
     * @since 2.8
     */
    public static <T> T requireNonEmpty(final T value, final String message) {
        if (isEmpty(value)) {
            throw new IllegalArgumentException(message);
        }
        return value;
    }

    public static int valueIsAtLeast(final int value, final int minValue) {
        if (value < minValue) {
            throw new IllegalArgumentException("Value should be at least " + minValue + " but was " + value);
        }
        return value;
    }
}

⏎ org/apache/logging/log4j/core/util/Assert.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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