Thread: Recursive media file algorithm

So I'm trying to program a mediafile scanner that can give me the extension, quality and mediatype(movie,tvshow -> online database search)
of files. Now everything works. I can recursively search through my whole external harddisk without a problem. It retrieves all files and does everything I want it to.
However when I try to scan the c:/ I think I run in to a permission problem because it throws a nullpointer exception while it does receive the files.

This is my recursion alghorithm:

public void getFiles(File file) {  //put files in list
        if (file.isDirectory() && (!file.isHidden())) {
            File[] folder = file.listFiles();
            recurse(folder);
        } else {
            listOfFiles.add(file);
        }
    }
 
    public void recurse(File[] file) {   //recursive search method
        for (File f : file) {
            if (f.isDirectory()) {
                recurse(f.listFiles());
            } else {
                listOfFiles.add(f);
            }
        }
    }

Here's what I've tried so far

 public void getFiles(File file) {  //put files in list
        if (file.isDirectory() && (!file.isHidden()) && file.canRead()
                && file.canWrite() && file.canExecute()) {
            File[] folder = file.listFiles();
            recurse(folder);
        } else {
            listOfFiles.add(file);
        }
    }
 
    public void recurse(File[] file) {   //recursive search method
        for (File f : file) {
            if (f.isDirectory()) {
                recurse(f.listFiles());
            } else {
                listOfFiles.add(f);
            }
        }
    }

Anyone know why it's failing?

full stacktrace

Exception in thread "main" java.lang.NullPointerException
	at VidScan.Model.VideoLibrary.recurse(VideoLibrary.java:37)
	at VidScan.Model.VideoLibrary.getFiles(VideoLibrary.java:30)
	at VidScan.View.Console.Console.<init>(Console.java:13)
	at VidScan.StartApp.main(StartApp.java:6)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)

What is the full stack trace? What line doe the error occur on? What exactly is it trying to access?

You didn't really answer my questions. What is the stack trace? What line does the error occur on? What exactly is it trying to access?

And what is being accessed on that line? What is its value?

Recommended reading: http://www.javaprogrammingforums.com...t-println.html

Okay, so what does that mean? What is null?

Also, you should check out the File API to understand what can be returned from the functions you're using: Java Platform SE 6

Originally Posted by mobinni

Well what you said didn't help directly, but it did give me the answer xD when recursing files you need try catch for unexpected errors. Such a rookie mistake #FML Thanks!!

That's probably not what you should be doing. Instead, you should attempt to understand why those errors are occurring, as it probably indicates a problem with your logic.

Seems to me it would be easier just to see if your program throws the same error when you tell it to specifically look at one of those files. I really doubt that would be the problem. I'm not on your system so I can't do your debugging for you, which is why I tried walking you through the process.