How do I add all the filenames under a certain folder to an arraylist using Java

Question

I have this much so far

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

 import org.pdfbox.util.Splitter;
 public class fileName {
     public static void main(String args[]){
         File file = new File("/Users/apple/Desktop/");
         String[] directories = file.list(new FilenameFilter(){

             @Override
             public boolean accept(File current, String name) {
                return new File(current, name).isDirectory();
             }
         });
 System.out.println(Arrays.toString(directories));
 ArrayList<String[]>SSOList = new ArrayList<String[]>();
     }
 }

It prints the names of all the files on my desktop but I want to add them to an arraylist. How do I do that?

possible duplicate of https://stackoverflow.com/questions/157944/create-arraylist-from-array — Michael Potter, Jun 07 '17 at 02:51
Possible duplicate of [Create ArrayList from array](https://stackoverflow.com/questions/157944/create-arraylist-from-array) — Michael Potter, Jun 09 '17 at 05:59

lonesome · Accepted Answer · 2017-06-09T02:00:33.627

1

It is very easy. You can use recursion as follows:

 private static void read(final File folder)  {

    for (final File fileEntry : folder.listFiles()) {
        if (fileEntry.isDirectory()) {
            read(fileEntry);
        } else {
       //Do something
            }
    }
}

edited Jun 09 '17 at 02:00

answered Jun 07 '17 at 03:29

lonesome

2,503
6
35
61

Great solution! Appreciate it – DylanK Jun 09 '17 at 01:56

score 1 · Answer 2 · answered Jun 07 '17 at 04:43

There are quite a few ways by which you can get the filenames in an ArrayList:

Use the Arrays.asList() method:

ArrayList<String> SSOList = new ArrayList<String>(Arrays.asList(directories));

Use the Collections utility class allAll method:

List<String> SSOList = new ArrayList<String>(directories.length); Collections.addAll(SSOList , directories);
Traverse the directories array again and add each value to the ArrayList SSOList.

Kepping in mind that these are to be done after you get the values in directories array.

slal · Answer 3 · 2017-06-07T15:17:06.290

0

ArrayList<String> SSOList =  new ArrayList<String>(Arrays.asList(directories))

or you can use:

Collections.addAll(SSOList, directories);

Also if SSOList is the name of the ArrayList you want the files to be stored in, I think you need to change it to an array list of Strings and not array list of array of Strings :

List<String>SSOList = new ArrayList<String>();

edited Jun 07 '17 at 15:17

answered Jun 07 '17 at 02:48

slal

2,657
18
29

How do I add all the filenames under a certain folder to an arraylist using Java

3 Answers3