/*
 * 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.helpers;

import java.nio.charset.Charset;

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

/**
 * Charset utilities.
 */
public final class Charsets {

    private Charsets() {
    }

    /**
     * Gets a Charset, starting with the preferred {@code charsetName} if supported, if not, use UTF-8, if not
     * supported, use the platform default.
     *
     * @param charsetName
     *            the preferred charset name
     * @return a Charset, not null.
     */
    public static Charset getSupportedCharset(final String charsetName) {
        Charset charset = null;
        if (charsetName != null) {
            if (Charset.isSupported(charsetName)) {
                charset = Charset.forName(charsetName);
            }
        }
        if (charset == null) {
            charset = Charset.isSupported("UTF-8") ? Charset.forName("UTF-8") : Charset.defaultCharset();
            if (charsetName != null) {
                StatusLogger.getLogger().error("Charset " + charsetName + " is not supported for layout, using " +
                    charset.displayName());
            }
        }
        return charset;
    }

}

/*
 * 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.helpers;

import java.nio.charset.Charset;

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

/**
 * Charset utilities.
 */
public final class Charsets {

    private static final String UTF_8 = "UTF-8";

    private Charsets() {
    }

    /**
     * Gets a Charset, starting with the preferred {@code charsetName} if supported, if not, use UTF-8, if not
     * supported, use the platform default.
     *
     * @param charsetName
     *            the preferred charset name
     * @return a Charset, not null.
     */
    public static Charset getSupportedCharset(final String charsetName) {
        Charset charset = null;
        if (charsetName != null) {
            if (Charset.isSupported(charsetName)) {
                charset = Charset.forName(charsetName);
            }
        }
        if (charset == null) {
            charset = Charset.isSupported(UTF_8) ? Charset.forName(UTF_8) : Charset.defaultCharset();
            if (charsetName != null) {
                StatusLogger.getLogger().error("Charset " + charsetName + " is not supported for layout, using " +
                    charset.displayName());
            }
        }
        return charset;
    }

}

Use a private constant instead of a magic string.