List All Files in a Directory in Java

In this section, we are going to learn how one can list all the files that are present in a directory. Note that a directory may contain a subdirectory, and that subdirectory may contain some files. We have to list these files, too, as these files are also part of the main directory. However, for the sake of simplicity, we will first look at the scenario where subdirectories are not present.

Directory without having Sub-directories

It means a folder is only containing files. Steps to print the files of a directory are mentioned below.

Step 1: Create a File Object for the directory.

Step 2: Obtain the array of files of that directory.

Step 3: Recursively, print the name of files (with extension) one by one.

Implementation

The following code prints the file names mentioned in the folder called Documents. The following snapshot shows the files present in the folder named Documents.

List All Files in a Directory in Java

FileName: DisplayFileExample.java

  // import statement  import java.io.File;  public class DisplayFileExample  {  public void printFileNames(File[] a, int i, int lvl)  {  // base case of the recursion  // i == a.length means the directory has   // no more files. Hence, the recursion has to stop  if(i == a.length)  {  return;  }  // checking if the encountered object is a file or not  if(a[i].isFile())  {  System.out.println(a[i].getName());  }  // recursively printing files from the directory  // i + 1 means look for the next file  printFileNames(a, i + 1, lvl);  }  // Main Method  public static void main(String[] argvs)  {  // Providing the full path for the directory  String path = “E:\Documents”;  // creating a file object  File fObj = new File(path);  // creating on object of the class DisplayFileExample  DisplayFileExample obj = new DisplayFileExample();  if(fObj.exists() && fObj.isDirectory())  {  // array for the files of the directory pointed by fObj  File a[] = fObj.listFiles();  // display statements  System.out.println(“= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =”);  System.out.println(“Displaying Files from the directory : ” + fObj);  System.out.println(“= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =”);  // Calling the method  obj.printFileNames(a, 0, 0);  }  }  }  

Output:

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =  Displaying Files from the directory: E:Documents  = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =  30004399657726 report 2.pdf  30004399657726 report.pdf  5010XXXXXX8778-13 Mar 2017 TO 12 Apr 2017.pdf  a b c.txt  asp.net tutorial.pdf  coding Standards.pdf  CS121Lec01.pdf  Databases for beginners.pdf  DBMS ME CS (gate2016.info).pdf  lec1.pdf  New Text Document.txt  Programming Interview Questions.docx  Rk - Database Management Systems 3rd Edition.pdf  slip201611605845.pdf  slip201611605845_2.pdf  Task 1.pdf  The Normal Forms2.ppt

Directory with Subdirectories

It means a folder contains files as well as subfolders. Steps to print the files of a directory and its subdirectory are mentioned below.

Step 1: Create a File Object for the directory.

Step 2: Obtain the array of files and subdirectory of that directory.

Step 3: If array[j] is a file, then display the file name and recursively go to the next element of the array[j].

Step 4: If array[j] is a directory, then display then directory name, and repeat from step 2.

Implementation

We have already seen the contents of the folder named Documents. Now, we create some folders inside Documents and store number of files in it. Observe the following snapshots.

List All Files in a Directory in Java

The above snapshot shows the Documents directory has 3 sub-directories named (New folder – 1, New folder – 2, New folder – 3).

The following snapshot shows the content of the folder named New folder – 1

List All Files in a Directory in Java

The following snapshot shows the content of the folder named New folder – 2

List All Files in a Directory in Java

The following snapshot shows the content of the folder named New folder – 3

List All Files in a Directory in Java

After the creation of folders, we can write the code on the basis of the steps defined above.

FileName: DisplayFileExample1.java

  // import statement  import java.io.File;  public class DisplayFileExample1  {  public void printFileNames(File[] a, int i, int lvl)  {  // base case of the recursion  // i == a.length means the directory has   // no more files. Hence, the recursion has to stop  if(i == a.length)  {  return;  }  // tabs for providing the indentation  // for the files of sub-directory  for (int j = 0; j < lvl; j++)  {  System.out.print(“t”);  }  // checking if the encountered object is a file or not  if(a[i].isFile())  {  System.out.println(a[i].getName());  }  // for sub-directories  else if(a[i].isDirectory())  {  System.out.println(“[” + a[i].getName() + “]”);  // recursion for sub-directories  printFileNames(a[i].listFiles(), 0, lvl + 1);  }  // recursively printing files from the directory  // i + 1 means look for the next file  printFileNames(a, i + 1, lvl);  }  // Main Method  public static void main(String[] argvs)  {  // Providing the full path for the directory  String path = “E:\Documents”;  // creating a file object  File fObj = new File(path);  // creating on object of the class DisplayFileExample1  DisplayFileExample1 obj = new DisplayFileExample1();  if(fObj.exists() && fObj.isDirectory())  {  // array for the files of the directory pointed by fObj  File a[] = fObj.listFiles();  // display statements  System.out.println(“= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =”);  System.out.println(“Displaying Files from the directory: ” + fObj);  System.out.println(“= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =”);  // Calling the method  obj.printFileNames(a, 0, 0);  }  }  }  

Output:

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =  Displaying Files from the directory: E:Documents  = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =  30004399657726 report 2.pdf  30004399657726 report.pdf  5010XXXXXX8778-13 Mar 2017 TO 12 Apr 2017.pdf  a b c.txt  asp.net tutorial.pdf  coding Standards.pdf  CS121Lec01.pdf  Databases for beginners.pdf  DBMS ME CS (gate2016.info).pdf  lec1.pdf  [New folder  - 1]          How to call private method from another class in java.docx          Java CardLayout.docx          Java GridBagLayout.docx          Java SpringLayout.docx          ordinal number in java.docx          tetrahedral number in java.docx  [New folder  - 2]          output onlinepngtools (13).png          output onlinepngtools (14).png          output onlinepngtools (15).png          output onlinepngtools (16).png          output onlinepngtools (17).png          output onlinepngtools (18).png  [New folder  - 3]          Java Regular Expressions.docx          n1 (7).png          n2 (3).png          n3.png          n4.png          String vs StringBuffer.docx          StringBuffer in Java.docx          StringBuffer vs StringBuilder.docx          StringBuilder in Java.docx  New Text Document.txt  Programming Interview Questions.docx  Rk - Database Management Systems 3rd Edition.pdf  slip201611605845.pdf  slip201611605845_2.pdf  Task 1.pdf  The Normal Forms2.ppt

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