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
This article is contributed by Gaurav Miglani. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
Attention reader! Don’t stop learning now. Get hold of all the important Java Foundation and Collections concepts with the Fundamentals of Java and Java Collections Course at a student-friendly price and become industry ready. To complete your preparation from learning a language to DS Algo and many more, please refer Complete Interview Preparation Course.
