`Directory` size

What is the total size of all files in a folder? In Java we can use the Files.newDirectoryStream method to access all Paths.

With the Path of each file, we can invoke Files.size to get a long value indicating the byte count of the file. This gives us a way to count up all the file sizes.

Example

This program introduces a method called getDirectorySize. It is a static method, so we do not need a Program instance to invoke it.

Step 1 We call Program.getDirectorySize with a directory relative to the current working directory we run the Java program in.

Step 2 Get convert the String argument into a path on the file system. This is necessary to call Files.newDirectoryStream.

Step 3 When we call FIles.newDirectoryStream, an exception may be thrown, so we can wrap the call in a try block.

Step 4 With a for-loop, we enumerate the Paths returned by newDirectoryStream. On each one, we call Files.size to get the required metadata.

Step 5 We return the total size we computed by summing up all the individual sizes from the files.

import java.io.*;
import java.nio.file.*;

public class Program {

    public static long getDirectorySize(String folder) {
        var sum = 0;

        // Step 2: get required path.
        var path = FileSystems.getDefault().getPath(folder);

        // Step 3: get DirectoryStream from path.
        try (var stream = Files.newDirectoryStream(path)) {
            // Step 4: enumerate the Paths and call size on each one, and sum up the sizes.
            for (Path entry : stream) {
                var size = Files.size(entry);
                sum += size;
            }
        } catch (IOException exception) {
        }

        // Step 5: return the total size.
        return sum;
    }

    public static void main(String[] args) {
        // Step 1: specify folder name in working directory.
        var size = Program.getDirectorySize("Movies");
        System.out.println("SIZE: " + size);
    }
}
SIZE: 504658

It is possible to combine multiple methods from the Files class to perform more complex tasks like summing up the size of files in a directory.

Directory size

Example

`Directory` size