Java program to List all files in a directory and nested sub-directories | Recursive approach

Prerequisites : File class

Given a main directory/folder, list all the files from it and if this directory have other nested sub-directories, list files from them also.

It is quite easy to observe simple recursion pattern in above problem.

Recursive Algorithm :

1. Create File object for main directory.
2. Get array of files for main directory.
3. If array[i] is a file :
   -> Print out file name.
4. If array[i] is a directory :
   -> Print out directory name.
   -> Get array of files for current sub-directory.
   -> Repeat the step 3 and 4 with current sub-directory.

5. Repeat the step 3 and 4 with next array[i].

// Recursive Java program to print all files
// in a folder(and sub-folders)

import java.io.File;

public class GFG 
{
     static void RecursivePrint(File[] arr,int index,int level) 
     {
         // terminate condition
         if(index == arr.length)
             return;
         
         // tabs for internal levels
         for (int i = 0; i < level; i++)
             System.out.print("\t");
         
         // for files
         if(arr[index].isFile())
             System.out.println(arr[index].getName());
         
         // for sub-directories
         else if(arr[index].isDirectory())
         {
             System.out.println("[" + arr[index].getName() + "]");
             
             // recursion for sub-directories
             RecursivePrint(arr[index].listFiles(), 0, level + 1);
         }
          
         // recursion for main directory
         RecursivePrint(arr,++index, level);
    }
    
    // Driver Method
    public static void main(String[] args)
    {
        // Provide full path for directory(change accordingly)  
        String maindirpath = "C:\\Users\\Gaurav Miglani\\Desktop\\Test";
                
        // File object
        File maindir = new File(maindirpath);
         
        if(maindir.exists() && maindir.isDirectory())
        {
            // array for files and sub-directories 
            // of directory pointed by maindir
            File arr[] = maindir.listFiles();
            
            System.out.println("**********************************************");
            System.out.println("Files from main directory : " + maindir);
            System.out.println("**********************************************");
            
            // Calling recursive method
            RecursivePrint(arr,0,0); 
       } 
    }
}

Output:

**********************************************
Files from main directory : C:\Users\Gaurav Miglani\Desktop\Test
**********************************************
Cormen.pdf
Extra-Items.pdf
XYZ.pdf
[Docs]
    A.docx
    B.doc
    C.docx
ABC.pdf
JKL.pdf
[sheets]
    XXX.csv
    YYY.csv
results.pdf
[Resumes]
    [Before2016]
        Resume2015.doc
        Resume2016.doc
        [Before2014]
            Resume2014.doc
    Resume2017.doc
    Resume2017.pdf
        QA.doc
Testing.pdf

 

Below is another recursive program. Here we use recursion only for nested sub-directories. For main directory files, we use foreach loop.

// Recursive Java program to print all files
// in a folder(and sub-folders)

import java.io.File;

public class GFG 
{
     static void RecursivePrint(File[] arr, int level) 
     {
         // for-each loop for main directory files
         for (File f : arr) 
         {
             // tabs for internal levels
             for (int i = 0; i < level; i++)
                 System.out.print("\t");
            
             if(f.isFile()) 
                 System.out.println(f.getName());
             
             else if(f.isDirectory()) 
             { 
                 System.out.println("[" + f.getName() + "]");
             
                 // recursion for sub-directories
                 RecursivePrint(f.listFiles(), level + 1);
             }
         }
    }
    
    // Driver Method
    public static void main(String[] args)
    {
        // Provide full path for directory(change accordingly)  
        String maindirpath = "C:\\Users\\Gaurav Miglani\\Desktop\\Test";
                
        // File object
        File maindir = new File(maindirpath);
         
        if(maindir.exists() && maindir.isDirectory())
        {
            // array for files and sub-directories 
            // of directory pointed by maindir
            File arr[] = maindir.listFiles();
            
            System.out.println("**********************************************");
            System.out.println("Files from main directory : " + maindir);
            System.out.println("**********************************************");
            
            // Calling recursive method
            RecursivePrint(arr, 0); 
       } 
    }
}

Output:

**********************************************
Files from main directory : C:\Users\Gaurav Miglani\Desktop\Test
**********************************************
Cormen.pdf
Extra-Items.pdf
XYZ.pdf
[Docs]
    A.docx
    B.doc
    C.docx
ABC.pdf
JKL.pdf
[sheets]
    XXX.csv
    YYY.csv
results.pdf
[Resumes]
    [Before2016]
        Resume2015.doc
        Resume2016.doc
        [Before2014]
            Resume2014.doc
    Resume2017.doc
    Resume2017.pdf
        QA.doc
Testing.pdf

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