code: /*
   * 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.commons.io.filefilter;
  
  import java.io.File;
  import java.io.Serializable;
  
  /**
   * This filter produces a logical NOT of the filters specified.
   *
   * @since Commons IO 1.0
   * @version $Revision: 1005099 $ $Date: 2010-10-06 17:13:01 +0100 (Wed, 06 Oct 2010) $
   * 
   * @author Stephen Colebourne
   * @see FileFilterUtils#notFileFilter(IOFileFilter)
   */
  public class NotFileFilter extends AbstractFileFilter implements Serializable {
      
      /** The filter */
      private final IOFileFilter filter;
  
      /**
       * Constructs a new file filter that NOTs the result of another filter.
       * 
       * @param filter  the filter, must not be null
       * @throws IllegalArgumentException if the filter is null
       */
      public NotFileFilter(IOFileFilter filter) {
          if (filter == null) {
              throw new IllegalArgumentException("The filter must not be null");
          }
          this.filter = filter;
      }
  
      /**
       * Returns the logical NOT of the underlying filter's return value for the same File.
       * 
       * @param file  the File to check
       * @return true if the filter returns false
       */
      @Override
      public boolean accept(File file) {
          return ! filter.accept(file);
      }
      
      /**
       * Returns the logical NOT of the underlying filter's return value for the same arguments.
       * 
       * @param file  the File directory
       * @param name  the filename
       * @return true if the filter returns false
       */
      @Override
      public boolean accept(File file, String name) {
          return ! filter.accept(file, name);
      }
  
      /**
       * Provide a String representaion of this file filter.
       *
       * @return a String representaion
       */
      @Override
      public String toString() {
          return super.toString() + "(" + filter.toString()  + ")";
      }
      
  }
  