Listing files tutorial not working?

Margsy

Hey I was hoping to use this jpg file listing tutorial in my program, but it doesn't seem to work- does anyone know how to fix it? http://wiki.processing.org/w/Listing_files

Rigth now, it's giving a NullPointerException here-

println(filenames.length + " jpg files in specified directory");

which I have figured means that filenames is probably not well declared. Or can't be read or something. I suspect it's because folder.list() is not really a thing- the reference seems to indicate it's only for fonts. Is it because the tutorial is old? Is there a way to update it?

Andddd once that's been figured out, is there a way to make it read any folder and not just the data one from the sketch (which I assume is what it does)?

Thanks so much for any tips on how to make this work!!!

(In case you're interested, I'm going to use it to display a bunch of images without having to write the name of each file in the code)

SilentAce

You first need to specify the path to the directory. If it is empty you get NullPointerException. To list all the folders you need a new filter that has isDirectory() inside. Then list() the folder path. Also note that the path has "/" instead of "\". The second one is for ignoring characters in a string. Here is the example

// The data path of the folder to look in (write your own)
java.io.File folder = new java.io.File(dataPath("C:/Users/Username/Desktop/sketchName"));

// let's set a filter (which returns true if file's extension is .jpg)
java.io.FilenameFilter jpgFilter = new java.io.FilenameFilter() {
  boolean accept(File dir, String name) {
    return name.toLowerCase().endsWith(".jpg");
  }
};

// list all the folders inside the main directory
String[] listFolders = folder.list(new java.io.FilenameFilter() {
  public boolean accept(File current, String name) {
    return new File(current, name).isDirectory();
  }
});

// list the files in the data folder, passing the filter as parameter
String[] filenames = folder.list(jpgFilter);
String[] foldernames = folder.list();

// get and display the number of jpg files
println(filenames.length + " jpg files in specified directory");
println(foldernames.length -1 + " folders in the specified directory");

// display the folder names
for(int i=0; i < foldernames.length-1; i++) {
  println(listFolders[i]);
}

// display the filenames
for (int i = 0; i < filenames.length; i++) {
  println(filenames[i]);
}

Margsy

Oh dear. Just adding something in the directory path. That was easy. Thanks ;;) It's kinda silly because I thought of doing it but then I got some weird errors because I didn't know about backslashes. The more you know...