Compute the size of a directory

import java.io.File;

public class What033 {

    public static void main(String[] args) {

        What033 w = new What033();

        File dir = new File("D:\\temp");

        System.out.println(w.getDirSizeInMegabytes(dir) + "MiB");

    }

    /**

     * It seems that a Directory itself will occupy 4K storage, and this depends

     * on different OS, here ignores this issue.

     *

     * @param dir

     * @return

     */

    long getDirSize(File dir) {

        long size = 0;

        if (dir.isFile()) {

            size = dir.length();

        }

        File[] subFiles = dir.listFiles();

        for (File file : subFiles) {

            if (file.isFile()) {

                size += file.length();

            } else {

                size += this.getDirSize(file);

            }

        }

        return size;

    }

    long getDirSizeInMegabytes(File dir) {

        return this.getDirSize(dir) / 1024 / 1024;

    }

}