Question

To implement a recursive algorithm to calculates the total directory size (in bytes) of the portion of the file system rooted at the given path.

Program will rely on the following methods of the class:

• new File(pathString) or new File(parentFile,childString)
• file.length() returns the immediate disk usage(measured in bytes)
• file.isDirectory() Returns true if the File instance represents a directory; false otherwise
• file.list() Return an array of strings designating the names of all entries within the given directory

Answer 1

The code is :

import java.io.File;

public class FileSize
{
   static long findSize(File[] arr,int index,long size)
   {
       if(index == arr.length)
           return size;
       if(arr[index].isFile())
           size = size + arr[index].length();
       else if(arr[index].isDirectory())
           size = size + findSize(arr[index].listFiles(), 0,0);
       return (size + findSize(arr,++index,0));
   }
   public static void main(String[] args)
   {
       String path = "/home/shrutina/DSAAssingments";
       File dir = new File(path);
       long size;
      
       if(dir.exists() && dir.isDirectory())
       {   File arr[] = dir.listFiles();
           size = findSize(arr,0,0);
           System.out.println("File size is "+size);
   }
   }
}
Output: