Recursive media file algorithm

[mobinni]

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)

[KevinWorkman]

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

[mobinni]

I'm trying to read every file (except hidden ones) off my C drive compare the file to the media formats such as: avi, mkv, etc... Then put them in a list
Problem is in the for loop in recurse according to the stack trace

[KevinWorkman]

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?

[mobinni]

The stacktrace is in my post and I'm trying to read each file off my C drive and determine if it's a videofile or not?
Line 37 in my code

        for (File f : file) {

That

[KevinWorkman]

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

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

[mobinni]

....
JmCR.sys
JmCrIcon.dll
jmcr_sd1.inf
jmcr.cat
JmCR.sys
JmCrIcon.dll
jmcr_sd1.inf
SdJmPCIE.dll
Setup.exe
setup.ini
silentsetup.bat
Version.txt
Exception in thread "main" java.lang.NullPointerException
	at VidScan.Model.VideoLibrary.recurse(VideoLibrary.java:38)
	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)

[KevinWorkman]

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

[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!!

[KevinWorkman]

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.

[mobinni]

Well it's more likely a problem with authentication. You see when going through my entire C:/ folder I'm also accessing files with certain priviliges it could be possible that my recursion algorithm stumbles on such files. I could alter my manifest file granting administrator privileges to test my theorie... Because the logic is simple: Take a file -> check if it's a folder. Yes? Test all the files in that folder and add files to list and so on. No? Add file to collection. I think it's probably authentication because on an external harddisk it can scan the whole thing without a problem and there are enough files on it.

[KevinWorkman]

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.

[mobinni]

I read the material you sent and will take it under advisement. Maybe try it out tomorrow. Thanks though! Don't want you to think I'm ungrateful