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

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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