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 has other nested sub-directories, list files from them. It is pretty easy to observe a simple recursion pattern in the above problem.

Algorithm :

1. Create a File object for the main directory.
2. Get an array of files for the main directory.
3. If array[i] is a file:
   • Print out the 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].

Example 1:

Java

// 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

Example 2: Below is another recursive program. Here we use recursion only for nested sub-directories. For main directory files, we use foreach loop.

Java

// 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

Example 3 –

Below is another iterative program to get all file name using Stack DS

Java

// Iterative Program to get all file names in Directory and
// SubDirectory

import java.io.*;

class GFG {
    public static void main(String[] args)
    {
        // provide complete path for directory(to be changed
        // accordingly)
        String mainDir = "c:\\GFG\\example";
        // File object
        File file = new File(mainDir);
        Stack<File> s = new Stack<>();
        s.push(file);
        // initially stack is not empty
        System.out.println("Content of Directory " + mainDir
                           + " is");
        while (!s.empty()) {
            File tmpF = s.pop();
            // check if it is a file or not
            if (tmpF.isFile()) {
                // print file name can code here according
                // to our need
                System.out.println(tmpF.getName());
            }
            else if (tmpF.isDirectory()) {
                // It's an directory hence list and push all
                // files in stack
                File[] f = tmpF.listFiles();
                for (File fpp : f) {
                    s.push(fpp);
                }
            } // else if ends here
        } // stack is not empty loop ends here
    } // main function ends here
}

Output:

Content of Directory c:\GFG\example is
example.txt
testTwo.java
testTwo.class
test.java
test.class
test.java
eg1.java
eg1.class
test.java
test.class
Students.java
Students.class

NOTE: The above code won’t compile on online IDE to compile and execute it download in your local system.