How to get the size of a directory in Java

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Problem Description

How to get the size of a directory?

Solution

Following example shows how to get the size of a directory with the help of FileUtils.sizeofDirectory(File Name) method of FileUtils class.

import java.io.File;
import org.apache.commons.io.FileUtils;

public class Main {
   public static void main(String[] args) {
      long size = FileUtils.sizeOfDirectory(new File("C:/Windows"));
      System.out.println("Size: " + size + " bytes");
   }
}

Result

The above code sample will produce the following result.

Size: 2048 bytes

The following is an another sample example to get the size of a directory in Java

import java.io.File;
import java.util.ArrayList;
 
public class Main {
   public static void main(String[] args) { 
      long folderSize = findSize("C:\\a");
      System.out.println("Size in byte :"+folderSize);
   } 
   public static long findSize(String path) { 
      long totalSize = 0;
      ArrayList<String> directory = new ArrayList<String>();
      File file = new File(path);
      
      if(file.isDirectory()) { 
         directory.add(file.getAbsolutePath());
         while (directory.size() > 0) {
            String folderPath = directory.get(0);
            System.out.println("Size of this :"+folderPath);
            directory.remove(0);
            File folder = new File(folderPath);
            File[] filesInFolder = folder.listFiles();
            int noOfFiles = filesInFolder.length;
            
            for(int i = 0 ; i < noOfFiles ; i++) { 
               File f = filesInFolder[i];
               if(f.isDirectory()) { 
                  directory.add(f.getAbsolutePath());
               } else { 
                  totalSize += f.length();
               } 
            } 
         } 
      } else { 
         totalSize = file.length();
      } 
      return totalSize;
   }
}

The above code sample will produce the following result.

Size of this :C:\a
Size of this :C:\a\b
Size of this :C:\a\b\c
Size of this :C:\a\b\c\d
Size in byte :0