/* * Copyright 1999-2005 The Apache Software Foundation. *  * Licensed 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.log4j.varia;import org.apache.log4j.Appender;import org.apache.log4j.Layout;import org.apache.log4j.spi.OptionHandler;import org.apache.log4j.spi.LoggingEvent;import org.apache.log4j.spi.ErrorHandler;import org.apache.log4j.spi.Filter;import org.apache.log4j.AppenderSkeleton;/**  * A NullAppender merely exists, it never outputs a message to any  * device.    * @author Ceki G&uuml;lc&uml;  */public class NullAppender extends AppenderSkeleton {  private static NullAppender instance = new NullAppender();  public NullAppender() {  }  /**    * There are no options to acticate.   * */  public void activateOptions() {  }  /**   * Whenever you can, use this method to retreive an instance instead   * of instantiating a new one with <code>new</code>.   * */  public NullAppender getInstance() {    return instance;  }  public void close() {  }  /**   * Does not do anything.    * */  public void doAppend(LoggingEvent event) {  }  /**   * Does not do anything.    * */  protected void append(LoggingEvent event) {  }  /**    * NullAppenders do not need a layout.      * */  public boolean requiresLayout() {    return false;  }}