Reading all text files in a directory in Java?

Question

How would I scan an entire folder in my Java code and then read each text file in to a separate array? What I'm trying to do is have a set of LocationNodes(class I created) on a map app that I'm creating for my college campus/side project for my resume.

When the code initializes, I want my app to scan for all text files in my "LocationTextFiles" folder. Each text file has 3 sets of text: Line 0 (the name of the location), Line 1 (Hours the building is open), and Line 2-EOF (description of the location). I then would take these lines stick them in a new LocationNode object every time and then create a new LocationNode object to repeat the process until all files that were found have been read.

What's the best way to go about doing this? I have the class set up with it's attributes (name, hoursText, and descriptionText), so I'm assuming this function that I would create would need to be a public method of this same LocationNode class?

score 2 · Answer 1 · answered Apr 29 '15 at 09:26

2

Here you go,

File folder = new File("/path/to/files");
File[] listOfFiles = folder.listFiles();

for (int i = 0; i < listOfFiles.length; i++) {
  File file = listOfFiles[i];
  if (file.isFile() && file.getName().endsWith(".txt")) {
String content = FileUtils.readFileToString(file);
    /* do somthing with content */
  } 
}

You can use array instead of content. But I would suggest don't do it, if you have huge number of files or each file is huge. When I huge, I mean the size exceed RAM size.

answered Apr 29 '15 at 09:26

Abhishek

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Thanks! I'll try this out. The files I'm using have very minimal text so an array might work. At most it's 20 lines of text max. – Palak Setia Apr 29 '15 at 09:33
I'm getting an error saying the compiler can not find a symbol and it points and arrow at "FileUtils"? – Palak Setia Apr 29 '15 at 11:40
You need to add External jar. See http://stackoverflow.com/questions/13166350/using-fileutils-in-eclipse for more details – Abhishek Apr 29 '15 at 12:21
So I've got the apache commons installed, but I keep getting exception errors, even when I write "throws ioexception"? any tips? – Palak Setia Apr 29 '15 at 13:35
You don't have to install it, just add the jar. What exception/error is your code throwing now? – Abhishek Apr 29 '15 at 14:52
Right now I'm getting a NullPointerException – Palak Setia Apr 29 '15 at 20:04
The NullPointerException is pointing to the for loop declaration? I think it has something to do with "listOfFiles.length" but I could be wrong – Palak Setia Apr 29 '15 at 21:11
Which line it is showing `NullPointerException`? You need to edit question and show us your code! – Abhishek Apr 30 '15 at 04:31

Reading all text files in a directory in Java?

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