1 /*
   2  * Copyright (c) 2007, 2009, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.nio.file;
  27 
  28 import java.nio.file.attribute.BasicFileAttributes;
  29 import java.io.IOException;
  30 import java.util.Objects;
  31 
  32 /**
  33  * A simple visitor of files with default behavior to visit all files and to
  34  * re-throw I/O errors.
  35  *
  36  * <p> Methods in this class may be overridden subject to their general contract.
  37  *
  38  * @param   <T>     The type of reference to the files
  39  *
  40  * @since 1.7
  41  */
  42 
  43 public class SimpleFileVisitor<T> implements FileVisitor<T> {
  44     /**
  45      * Initializes a new instance of this class.
  46      */
  47     protected SimpleFileVisitor() {
  48     }
  49 
  50     /**
  51      * Invoked for a directory before entries in the directory are visited.
  52      *
  53      * <p> Unless overridden, this method returns {@link FileVisitResult#CONTINUE
  54      * CONTINUE}.
  55      */
  56     @Override
  57     public FileVisitResult preVisitDirectory(T dir, BasicFileAttributes attrs)
  58         throws IOException
  59     {
  60         Objects.nonNull(dir);
  61         Objects.nonNull(attrs);
  62         return FileVisitResult.CONTINUE;
  63     }
  64 
  65     /**
  66      * Invoked for a file in a directory.
  67      *
  68      * <p> Unless overridden, this method returns {@link FileVisitResult#CONTINUE
  69      * CONTINUE}.
  70      */
  71     @Override
  72     public FileVisitResult visitFile(T file, BasicFileAttributes attrs)
  73         throws IOException
  74     {
  75         Objects.nonNull(file);
  76         Objects.nonNull(attrs);
  77         return FileVisitResult.CONTINUE;
  78     }
  79 
  80     /**
  81      * Invoked for a file that could not be visited.
  82      *
  83      * <p> Unless overridden, this method re-throws the I/O exception that prevented
  84      * the file from being visited.
  85      */
  86     @Override
  87     public FileVisitResult visitFileFailed(T file, IOException exc)
  88         throws IOException
  89     {
  90         Objects.nonNull(file);
  91         throw exc;
  92     }
  93 
  94     /**
  95      * Invoked for a directory after entries in the directory, and all of their
  96      * descendants, have been visited.
  97      *
  98      * <p> Unless overridden, this method returns {@link FileVisitResult#CONTINUE
  99      * CONTINUE} if the directory iteration completes without an I/O exception;
 100      * otherwise this method re-throws the I/O exception that caused the iteration
 101      * of the directory to terminate prematurely.
 102      */
 103     @Override
 104     public FileVisitResult postVisitDirectory(T dir, IOException exc)
 105         throws IOException
 106     {
 107         Objects.nonNull(dir);
 108         if (exc != null)
 109             throw exc;
 110         return FileVisitResult.CONTINUE;
 111     }
 112 }