listFiles() in Java fails to get all files

Question

I wrote this function and it seemed okey but it fails if there are more than one folders in the current directory and no files. It enters only the first folder and does it job there and ignores the other folders. How can I fix this bug?

public static void getAllFiles(File folder, List<File> result) {
    File[] listOfFiles = folder.listFiles();
    for (int i = 0; i < listOfFiles.length; i++) {
        if (listOfFiles[i].isFile()) {
           result.add(listOfFiles[i]);
        }
        if (listOfFiles[i].isDirectory()) {
            getAllFiles(listOfFiles[i], result);
        }
    }
}

You should check this answer: http://stackoverflow.com/a/1846349/380161 — Anupam Saini, Feb 18 '15 at 10:07
Well, the best answer there and the second they give a bug. .listFiles() bugs if there are for example only two folders in the starting folder. That's my problem and they use the same function. — Stanislav Bozhanov, Feb 18 '15 at 10:13
If that's the case please leave a comment so that others are aware of the limitations with that approach. — Anupam Saini, Feb 18 '15 at 10:17
what version of java are you using? with Java 8, you can use the following http://docs.oracle.com/javase/tutorial/essential/io/walk.html — EpicPandaForce, Feb 18 '15 at 10:20
What are the two directories inside? This method will not list a parent directory. — enterbios, Feb 18 '15 at 10:20

Daniel Michalski · Answer 1 · 2015-02-18T11:08:47.027

Maybe you should try walkFileTree method from NIO.2:

public List<Path> findAllFilesInDirectory(Path pathToDir) throws IOException {
    final List<Path> pathsToFiles = new ArrayList<>();

    Files.walkFileTree(pathToDir, new SimpleFileVisitor<Path>() {
        @Override
        public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
            if (Files.isRegularFile(file)) {
                pathsToFiles.add(file);
            }
            return FileVisitResult.CONTINUE;
        }
    });

    return pathsToFiles;
}

To using NIO.2 You have to have at least a Java 1.7 version.

Documentation:

http://docs.oracle.com/javase/tutorial/essential/io/walk.html

Tutorials:

http://www.javabeat.net/visiting-all-the-files-and-directories-for-a-directory-in-java-using-nio2/

http://www.srccodes.com/p/article/20/java-file-and-directory-operations-made-easy-in-jdk7

score 1 · Answer 2 · answered Feb 18 '15 at 10:13

1

I tried it as:

public void listf(String directoryName, List<File> files){ File directory = new File(directoryName) // get all the files from a directory File[] fList = directory.listFiles(); for (File file : fList) { if (file.isFile()) { files.add(file); } else if (file.isDirectory()) { listf(file.getAbsolutePath(), files); } } }

answered Feb 18 '15 at 10:13

Abhi

341
7
15

Why are you converting a File to String to pass it to recursive call and there convert it from String to File again? – enterbios Feb 18 '15 at 10:17
I was passing folder location as string, we can directly pass he file as well like `else if (file.isDirectory()) {listf(file, files);}` and change the method definition to `public void listf(File file,List files)` – Abhi Feb 18 '15 at 10:25
1

@Abhi But why? `File` is already an abstract representation of the file/folder, which contains all the information required...you just seem to be throwing away data just to recreate it... – MadProgrammer Feb 18 '15 at 10:29

score 1 · Answer 3 · answered Feb 18 '15 at 10:28

I have no issue with your code, but you might be running into issues with "symbolic links" (like "My Documents" on Windows) which, while they seem to appear as directories, Java can't resolve them and calling listXxx will return null.

Having said that, you could also try using something like...

public static void getAllFiles(File folder, List<File> result) {
    System.out.println(folder.getName());
    File[] listOfFiles = folder.listFiles(new FileFilter() {
        @Override
        public boolean accept(File pathname) {
            return pathname.isFile();
        }
    });
    if (listOfFiles != null && listOfFiles.length > 0) {
        result.addAll(Arrays.asList(listOfFiles));
    }
    File[] listOfFolders = folder.listFiles(new FileFilter() {
        @Override
        public boolean accept(File pathname) {
            return pathname.isDirectory();
        }
    });
    for (File subFolder : listOfFolders) {
        getAllFiles(subFolder, result);
    }
}

instead to list the files and directories.

I believe the new nio2 (Files and Paths API) has a fix for it...

listFiles() in Java fails to get all files

3 Answers3

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