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 accepts <code>File</code>s that can be read.
   * <p>
   * Example, showing how to print out a list of the 
   * current directory's <i>readable</i> files:
   *
   * <pre>
   * File dir = new File(".");
   * String[] files = dir.list( CanReadFileFilter.CAN_READ );
   * for ( int i = 0; i &lt; files.length; i++ ) {
   *     System.out.println(files[i]);
   * }
   * </pre>
   *
   * <p>
   * Example, showing how to print out a list of the 
   * current directory's <i>un-readable</i> files:
   *
   * <pre>
   * File dir = new File(".");
   * String[] files = dir.list( CanReadFileFilter.CANNOT_READ );
   * for ( int i = 0; i &lt; files.length; i++ ) {
   *     System.out.println(files[i]);
   * }
   * </pre>
   *
   * <p>
   * Example, showing how to print out a list of the 
   * current directory's <i>read-only</i> files:
   *
   * <pre>
   * File dir = new File(".");
   * String[] files = dir.list( CanReadFileFilter.READ_ONLY );
   * for ( int i = 0; i &lt; files.length; i++ ) {
   *     System.out.println(files[i]);
   * }
   * </pre>
   *
   * @since Commons IO 1.3
   * @version $Revision: 659817 $
   */
  public class CanReadFileFilter extends AbstractFileFilter implements Serializable {
      
      /** Singleton instance of <i>readable</i> filter */
      public static final IOFileFilter CAN_READ = new CanReadFileFilter();
  
      /** Singleton instance of not <i>readable</i> filter */
      public static final IOFileFilter CANNOT_READ = new NotFileFilter(CAN_READ);
      
      /** Singleton instance of <i>read-only</i> filter */
      public static final IOFileFilter READ_ONLY = new AndFileFilter(CAN_READ,
                                                  CanWriteFileFilter.CANNOT_WRITE);
      
      /**
       * Restrictive consructor.
       */
      protected CanReadFileFilter() {
      }
      
      /**
       * Checks to see if the file can be read.
       * 
       * @param file  the File to check.
       * @return <code>true</code> if the file can be
       *  read, otherwise <code>false</code>.
       */
      @Override
      public boolean accept(File file) {
          return file.canRead();
      }
      
  }
  