Java - Get a directory's size

There are few ways to get a directory’s size.

Solution 1

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Sum up all the files’ size in the directory.

    ...
    public static long dirSize(File dir) {
        long size = 0;
        for (File file : dir.listFiles()) {
            if (file.isFile()) {
                size += file.length();
            } else {
                size += dirSize(file);
            }
        }
        return size;
    }
    ...

...

public static long dirSize(File dir) {

long size = 0;

for (File file : dir.listFiles()) {

if (file.isFile()) {

size += file.length();

} else {

size += dirSize(file);

}

return size;

}

...

Solution 2

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Java 7 style

    ...
    public static long dirSize(String path) throws IOException {
        AtomicLong dirSize = new AtomicLong(0);
        Path dir = Paths.get(path);

        Files.walkFileTree(dir, new SimpleFileVisitor<Path>() {
            public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                dirSize.addAndGet(attrs.size());
                return FileVisitResult.CONTINUE;
            }
        });

        return dirSize.longValue();
    }
    ...

...

public static long dirSize(String path) throws IOException {

AtomicLong dirSize = new AtomicLong(0);

Path dir = Paths.get(path);

Files.walkFileTree(dir, new SimpleFileVisitor<Path>() {

public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {

dirSize.addAndGet(attrs.size());

return FileVisitResult.CONTINUE;

}

});

return dirSize.longValue();

}

...

Solution 3

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Java 8 style

    ...
    public static long dirSize(String path) throws IOException {
        Path p1 = Paths.get(path);
        return Files.walk(p1).mapToLong(p -> p.toFile().length()).sum();
    }
    ...

...