Walk a directory/Recursively: Difference between revisions

module std.file provideprovides different walk directory functions (listdir).<br>

This one recursively walkwalks the directory, which can either match by regular expression or unix shell style pattern.

This one does not itself walk into a sub directory, but can be recursive by a callback delegate function.

<java>import java.io.File;

public class MainEntry {

public static void main(String[] args) {

walkin(new File("/home/user")); //Replace this with a suitable directory

}

/**

* Recursive function to descentdescend into the directory tree and find all the filefiles

* that end with ".mp3"

* @param dir A file object defining the top directory

**/

public static void walkin(File dir) {

String pattern = ".mp3";

File listFile[] = dir.listFiles();

if(listFile != null) {

for(int i=0; i<listFile.length; i++) {

if(listFile[i].isDirectory()) {

walkin(listFile[i]);

} else {

if(listFile[i].getName().endsWith(pattern)) {

System.out.println(listFile[i].getPath());

}

}

}

}

}

BuiltinBuilt-in procedure sys_file_match searches directories or directory

Class ''RichFile'' gets a ''java.io.File'' in constructor. Its two methods returnsreturn ''Iterable''s on items of type File. ''children'' allow iterations on the direct children (empty if file is not a directory). ''andTree'' contains a file and all files below, as a concatenation (''++'') of a a sequence which contains only a file (''Seq.single'') and actual descendants. MethodThe method ''flatMap'' in Iterable takes a function argument which associates each item (''child'') to another Iterable (''andTree'' called recursively on that child) and returns the concatenation of those iterables.

The purpose of the object ''RichFile'' is to publish the implicit method ''toRichFile''. When this method is available in scope (after ''import RichFile.toRichFile'' or ''import RichFile._''), it is called behind the scene when a method of class ''RichFile'' is called on an instance of type File : with f of type File, code ''f.children'' (resp. ''f.andTree'') becomes ''toRichFile(f).children'' (resp. ''toRichFile(f).andTree''). It is as if class File had been added the methods of class RichFile.