SimpleFileVisitor
.
import java.io.IOException; import java.nio.file.FileVisitResult; import java.nio.file.FileVisitor; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.nio.file.SimpleFileVisitor; import java.nio.file.attribute.BasicFileAttributes; /** Recursive listing with SimpleFileVisitor in JDK 7. */ public final class FileListingVisitor { public static void main(String... args) throws IOException{ String ROOT = "C:\\test"; FileVisitor<Path> fileProcessor = new ProcessFile(); Files.walkFileTree(Paths.get(ROOT), fileProcessor); } private static final class ProcessFile extends SimpleFileVisitor<Path> { @Override public FileVisitResult visitFile( Path file, BasicFileAttributes attrs ) throws IOException { System.out.println("Processing file:" + file); return FileVisitResult.CONTINUE; } @Override public FileVisitResult preVisitDirectory( Path dir, BasicFileAttributes attrs ) throws IOException { System.out.println("Processing directory:" + dir); return FileVisitResult.CONTINUE; } } }Older style, JDK 6-
The File
class has methods for listing the contents of a single directory, such
as list
and listFiles
, but there is no method for listing
all files in a directory tree.
Here's a simple utility which returns a sorted List
of File
objects which reside under a given root directory. It uses recursion.
import java.util.*; import java.io.*; /** * Recursive file listing under a specified directory. * * @author javapractices.com * @author Alex Wong * @author anonymous user */ public final class FileListing { /** * Demonstrate use. * * @param args - <tt>args[0]</tt> is the full name of an existing * directory that can be read. */ public static void main(String... args) throws FileNotFoundException { File startingDirectory= new File(args[0]); FileListing listing = new FileListing(); List<File> files = listing.getFileListing(startingDirectory); //print out all file names, in the the order of File.compareTo() for(File file : files){ System.out.println(file); } } /** * Recursively walk a directory tree and return a List of all * Files found; the List is sorted using File.compareTo(). * * @param startingDir is a valid directory, which can be read. */ public List<File> getFileListing( File startingDir ) throws FileNotFoundException { validateDirectory(startingDir); List<File> result = getFileListingNoSort(startingDir); Collections.sort(result); return result; } // PRIVATE private List<File> getFileListingNoSort( File startingDir ) throws FileNotFoundException { List<File> result = new ArrayList<>(); File[] filesAndDirs = startingDir.listFiles(); List<File> filesDirs = Arrays.asList(filesAndDirs); for(File file : filesDirs) { result.add(file); //always add, even if directory if (! file.isFile()) { //must be a directory //recursive call! List<File> deeperList = getFileListingNoSort(file); result.addAll(deeperList); } } return result; } /** * Directory is valid if it exists, does not represent a file, and can be read. */ private void validateDirectory ( File directory ) throws FileNotFoundException { if (directory == null) { throw new IllegalArgumentException("Directory should not be null."); } if (!directory.exists()) { throw new FileNotFoundException("Directory does not exist: " + directory); } if (!directory.isDirectory()) { throw new IllegalArgumentException("Is not a directory: " + directory); } if (!directory.canRead()) { throw new IllegalArgumentException("Directory cannot be read: " + directory); } } }
>java -cp . FileListing "C:\\TEMP\\" C:\\TEMP\\Hokkaido.txt C:\\TEMP\\Honshu.txt C:\\TEMP\\mb C:\\TEMP\\mb\\Kyushu.txt C:\\TEMP\\mb\\Shikoku.txt