Java Program to Get the Size of a Directory

The size of files in Java can be obtained using the File class. The in-built function of ‘fileName.length()’ is used to find size of file in Bytes. The directory may contain ‘N’ number of files, for calculating the size of the directory summation of the size of all the files is required.

length() Method:

length() method in the object of the file class is returning the file size in long(datatype) format. The file size is in a unit of Byte.

Return Type: long

Syntax:

java.io.File file = new java.io.File("file_name.txt");
file.length();

Working:

1. If the file exists then the function return the size of the file
2. Else the function returns null.

However, the size of the file can be display in Mega, Kilo units using unit conversion.

Java

// Java program to Get the size of a directory

import java.io.File;

class GFG {
    private static long getFolderSize(File folder)
    {
        long length = 0;

        // listFiles() is used to list the
        // contents of the given folder
        File[] files = folder.listFiles();

        int count = files.length;

        // loop for traversing the directory
        for (int i = 0; i < count; i++) {
            if (files[i].isFile()) {
                length += files[i].length();
            }
            else {
                length += getFolderSize(files[i]);
            }
        }
        return length;
    }

    // Driver Code
    public static void main(String[] args)
    {
        // Creating an instances of file class
        File file1 = new File("/home/mayur/Downloads");

        long size = getFolderSize(file1);
        // Size of folder in Bytes
        System.out.println("Size of " + file1 + " is "
                           + size + " B");
        // Size of folder in Kilobytes
        System.out.println("Size of " + file1 + " is "
                           + (double)size / 1024 + " KB");
        // Size of folder in Megabytes
        System.out.println("Size of " + file1 + " is "
                           + (double)size / (1024 * 1024)
                           + " MB");
    }
}

Output: