FileTreeIterator

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com.bristle.javalib.io
Class FileTreeIterator

java.lang.Object
  com.bristle.javalib.io.FileTreeIterator

All Implemented Interfaces:: Iterator

public class FileTreeIterator
extends Object
implements Iterator
extends Object
implements Iterator

This class implements an iterator for a directory tree of files and subdirectories. Within each subdirectory, it returns the immediate children (files and subdirectories) in case-insensitive alphabetic order. However, after returning each subdirectory, it returns the contents of the subdirectory, recursively, before continuing with the remaining siblings of that subdirectory. That is, it performs a "depth-first pre-order left-to-right" traversal. It does not return the top-level directory that was originally specified for traversal -- only its descendants.

Usage:
   - The typical scenario for using this class is:
       for (Iterator i = new FileTreeIterator("/dir"); i.hasNext(); )
       {
           File file = (File)i.next();
           doSomething(file);
       }

   - See the source code of the inner Tester class for more examples.
  
Assumptions:
Effects:
       - None.  Iterates over the directory tree, but does not change it.
Anticipated Changes:
       - Currently iterates forward only.  May add hasPrev() and prev() to 
         support reverse iteration and reversing during an iteration. 
       - May add support for resetting the iteration to a specified index 
         within the current subdirectory (the 3rd file, 5th file, etc.)
       - May add support for querying the index within the current 
         subdirectory.
       - Currently caches the entire set of filenames in a single directory,
         internally as an array of Strings.  May add an option to cache less
         and retrieve more directly from the filesystem on each iteration.
       - May add new constructor with a FilenameFilter parameter, so the 
         iterator returns a set of Files filtered by name.
       - May add new constructor with a FileFilter parameter, so the 
         iterator returns a set of Files filtered by other File properties.
         Note:  Supporting FileFilter will be easiest to do by switching 
                internally from File.list() to File.listFiles(), but that
                will make it harder to sort by filename.
       - May add additional traversal orders:
         - breadth-first, instead of depth-first
         - case-sensitive, instead of case-insensitive
         - post-order, instead of pre-order
         - right-to-left, instead of left-to-right     
       - May add a limit on the depth to traverse, so caller can limit a
         traversal to children only, children and grandchildren only, etc. 
Notes:
Implementation Notes:
Portability Issues:
Revision History:
   $Log$

Nested Class Summary
`static class`	`FileTreeIterator.Tester` Each class contains a Tester inner class with a main() for easier unit testing.

Constructor Summary
`FileTreeIterator(String strDirectoryName)` Constructor.

Method Summary
`boolean`	`hasNext()` Returns true if there are more Files to be iterated; false otherwise.
`Object`	`next()` Returns the next File in the iteration.
`void`	`remove()` Not implemented.

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail