Java Directory Size
In this post, we will learn how to get the Java directory size or size of a folder in Java using Java 7, Java 8 and Apache Commons API.
1. Get Size Using Java 7
We will be using Files.walkFileTree() method to recursively transverse through the files/directory to calculate the size.
public class DirectorySizeJava7 {
public static void main(String[] args) throws IOException {
Path rootDirectory= Paths.get("/Users/umesh/personal/tutorials/source/bootstrap");
AtomicLong size= new AtomicLong(0);
Files.walkFileTree(rootDirectory, new SimpleFileVisitor<Path>(){
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
throws IOException{
size.addAndGet(attrs.size());
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFileFailed(Path file, IOException exception)
throws IOException
{
//log exception
throw exception;
}
@Override
public FileVisitResult postVisitDirectory(Path dir, IOException exception) {
//log exception for error in reading file if exception is not null
return FileVisitResult.CONTINUE;
}
});
System.out.println("size of the folder is :: " + size);
}
}Output
the size of the folder is:: 1650691
I have used AtomicLong in above example to store size, which guarantees that the value can be used in a concurrent environment.
2. Get Size Using Java 8
We will be using Stream API along with Lambda expression provided by Java 8 to calculate the size of the folder.
public class DirectorySizeJava8 {
public static void main(String[] args) throws IOException {
Path rootDirectory = Paths.get("/Users/umesh/personal/tutorials/source/bootstrap");
long directorySize = Files.walk(rootDirectory)
.map(f -> f.toFile())
.filter(f -> f.isFile())
.mapToLong(f -> f.length()).sum();
}
}
We used stream API and making sure to filter out all directories by using filter(f -> f.isFile()). Please be aware that length method is not guaranteed to be 0 for directories.
We converted the result to LongStream by using mapToLong method and finally summed up the results to get the size.
Output
the size of the directory is::1650691
Note
Keep in mind following information while using walkFileTree or walk method under Java 7 and Java 8
- Underlying Java Security Manager can throw an exception in case we do not have permission to access it.
- Symbolic links can lead to infinite loop issue.
3. Get Size Using Apache Commons
Apache Commons IO’s FileUtils class provide a clean way to calculate the size of a given directory.
public class DirectorySizeApacheCommons {
public static void main(String[] args) {
File rootDirectory = new File("/Users/umesh/personal/tutorials/source/bootstrap");
long size= FileUtils.sizeOfDirectory(rootDirectory);
System.out.println("The Size of directory is:: "+size);
}
}Output
The Size of directory is:: 1650691
You need to be aware of the following
- You have to check if the file is directory else API will throw IllegalArgumentException.
- It might also throw IllegalArgumentException if the directory is being concurrently modified. Check IO-449.
4. Get Size Readable format
Printing information in human readable format is always a preferred way. Here is a small programme to print size information obtained in this post in human readable format.
public class DirectorySizeApacheCommons {
public static void main(String[] args) {
File rootDirectory = new File("/Users/umesh/personal/tutorials/source/bootstrap");
long size= FileUtils.sizeOfDirectory(rootDirectory);
readableFileSize(size);
}
public static void readableFileSize(long size){
final String[] units = new String[] { "B", "kB", "MB", "GB", "TB" };
int unitGroups = (int) (Math.log10(size)/Math.log10(1024));
System.out.println(new DecimalFormat("#,##0.#").format(size/Math.pow(1024, unitGroups)) + " " + units[unitGroups]);
}
}All the code of this article is available Over on Github. This is a Maven-based project.
References