Java: How to list the files in a directory

Java file directory list FAQ: How do I create a list of files in a directory using Java?

I use the Apache FileUtils class for a lot of needs like this, but here’s a quick example of a Java class that show how to create a list of all files in a directory using just the Java File class. Specifically, this example shows how to list all the files in a directory, store those filenames in a String array, and then print the array.

My Java directory “list files” class

Here’s the source code for this “list files in a directory” Java class:

import java.io.File;
import java.util.Arrays;

public class DirectoryTestMain
{
  public static void main(String[] args)
  {
    // create a file that is really a directory
    File aDirectory = new File("C:/temp");

    // get a listing of all files in the directory
    String[] filesInDir = aDirectory.list();

    // sort the list of files (optional)
    // Arrays.sort(filesInDir);

    // have everything i need, just print it now
    for ( int i=0; i<filesInDir.length; i++ )
    {
      System.out.println( "file: " + filesInDir[i] );
    }
  }
}

Discussion: Java directory files list example

I won’t get into a detailed discussion of this Java file/directory list example, but I will add a few points here to the comments that are shown in the code:

• This is a complete Java program. Just compile and run this class, and assuming that you have a directory named "C:/temp", you'll be able to get a listing of all the files in that directory.
• On Unix and Linux systems just specify the directory as normal, i.e., using something like /tmp instead of using the DOS C:/temp directory syntax.
• If the directory name you specify doesn't really exist, this code will throw a NullPointerException, so you have to be careful of that.
• I just ran this code against my home directory on a Linux computer, and it does list all the "hidden" files in my home directory. ("Hidden files" are all the filenames that begin with a decimal, i.e., filenames like .bash_profile.)

I can’t think of anything else to add right now, but if you have any questions or comments, just leave them in the comments section below and I'll get back with you.