Java Program to Get the Size of a Directory

The Java program used to get the size of a directory can calculate the total size of a directory and all the files and folders inside it using a recursive approach. By using this program, one can obtain valuable insights into the size of a directory.

Algorithm

Declare a private static method getDirectorySize that recursively calculates the size of a directory by iterating through all its contents, both files and directories.
Inside getDirectorySize, use the listFiles method of the File class to obtain an array of all the files and directories inside the given directory.
Loop through each file and directory in the array and add the file size to a running total if it's a file, or recursively call getDirectorySize if it's a directory.
In the main method, create a File object for the directory whose size you want to calculate and call getDirectorySize to get the size in bytes.
Convert the size to kilobytes and megabytes and print the results, along with the number of files and directories in the directory and its last modified time.

Implementation

Filename: DirectoryFile.java

import java.io.File;
public class DirectoryFile {
// Recursively calculate the size of a directory
private static long getDirectorySize(File directory) {
    long size = 0;

    // Get an array of all the files and directories inside the given directory
    File[] directoryContents = directory.listFiles();

    // If the directory is empty, return a size of 0
    if (directoryContents == null) {
        return 0;
    }

    // Loop through each file and directory
    for (File file : directoryContents) {
        // If it's a file, add its size to the total size
        if (file.isFile()) {
            size += file.length();
        } 
        // If it's a directory, recursively call getDirectorySize to calculate its size
        else if (file.isDirectory()) {
            size += getDirectorySize(file);
        }
    }

    return size;
}

public static void main(String[] args) {
    // Create a File object for the directory whose size we want to calculate
    File directory = new File("C:\\Users\\maddu\\OneDrive\\Desktop\\Watcher");

    // Get the size of the directory in bytes
    long sizeInBytes = getDirectorySize(directory);

    // Convert the size to kilobytes and megabytes
    double sizeInKilobytes = sizeInBytes / 1024.0;
    double sizeInMegabytes = sizeInKilobytes / 1024.0;

    // Print the size of the directory in bytes, kilobytes, and megabytes
    System.out.println("Size of directory " + directory.getAbsolutePath() + ":");
    System.out.println("  " + sizeInBytes + " bytes");
    System.out.println("  " + sizeInKilobytes + " KB");
    System.out.println("  " + sizeInMegabytes + " MB");

    // Print the number of files and directories in the directory
    int numFiles = 0;
    int numDirectories = 0;

    for (File file : directory.listFiles()) {
        if (file.isFile()) {
            numFiles++;
        } else if (file.isDirectory()) {
            numDirectories++;
        }
    }

    System.out.println("Number of files: " + numFiles);
    System.out.println("Number of directories: " + numDirectories);

    // Print the last modified time of the directory
    long lastModified = directory.lastModified();
    System.out.println("Last modified: " + lastModified);
}
}

Output:

Size of directory C:\Users\maddu\OneDrive\Desktop\Watcher:
  251475 bytes
  245.5810546875 KB
  0.23982524871826172 MB
Number of files: 10
Number of directories: 0
Last modified: 1682263462278

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