Recursive File List - Help me problem solve please
 

Hello

My recursive file scan is not doing what I want it to do.

I want it to be able to go through all roots (drives)...

With no user intervention, so without including "C:\\" or "." as a string in the source, or without a TextIO.java class.

import java.io.*;

import java.util.*;

 

public class RecursiveFileListAttemp1 {

    public static void main(String[] args) {

        File f = new File("C:\\");  

        search(f);

    }



    public static void search(File f) {  

        if ( !f.exists() ) return; 

        String name = f.getName(); 

        if ( f.isDirectory() ) {

        File[] files = f.listFiles();

        for( int i = 0 ; i < files.length; i++ ) {

        search( files[i] );

            }

        }

    }

}

At the moment I just get a null pointer exception...

I dont understand where Ive gone wrong in the code:
if its a file --> return the file name --> if its a directory --> list the files in the directory

Help please!

Re: Recursive File List - Help me problem solve please
 

Hello,

Code is working perfectly! No NPException. Using Eclipse SDK Version: 3.4.0.

Best of luck!

Re: Recursive File List - Help me problem solve please
 

File has a method that returns all the system "roots". See the API docs for File.

Re: Recursive File List - Help me problem solve please
 

really thats interesting punnetkay i wonder why

but it needs to work for me!

post above: thanks for that, but I dont want to list the roots I want to list the files and files in directories that are in all directories on a computer.

I think Ive got some stable code now. But I still want to know how to recursive scan the whole computer and not just a drive. At the moment I'm able to scan "C:\\" or "D:\\" and not both, does any one know how I can make that work?

Re: Recursive File List - Help me problem solve please
 

Then what was this?

As that is the part I was responding to. You will need to use that.

See above. You can only "recursively" scan each drive/root one at a time. But you can loop over what the above mentioned method returns.

Why does no one ever listen to what I say?

Re: Recursive File List - Help me problem solve please
 

Hello again,

And again its working fine for me.

        public static void main(String[] args) {

        for(File file : File.listRoots()){ // listRoots() method return list of drives. array of File type.

                search(file);

        }

    }



    public static void search(File f) {  

        if ( !f.exists() ) return; 

        String name = f.getName();

        System.out.println(name);

        if ( f.isDirectory() ) {

        File[] files = f.listFiles();

        for( int i = 0 ; i < files.length; i++ ) {

        search( files[i] );

            }

        }

    }

Regards,

Re: Recursive File List - Help me problem solve please
 

The NPE (as the OP already knows from his post on www.java-forums.com (or is it org?)) is because listFiles will return null on an empty directory so he needs to add an if statement to check for that.

Re: Recursive File List - Help me problem solve please
 

can I add a equals() statement in the code above and from that print to the terminal window files that occur on more than one instance on the recursive scan?

Re: Recursive File List - Help me problem solve please
 

Detection of duplicate files isn't that simple; refer a similar thread. If that's not what you intend, a bit more explanation is needed.

Re: Recursive File List - Help me problem solve please
 

lol i started that thread but ignore that one for now lol

anyways

thanks masijade for your reply

i tried something new

modified code below

     public static void search(File f) {

        if ( !f.exists() ) return; 

        String name = f.getName();

        System.out.println(name);

        if ( f.isDirectory() ) {

        File[] files = f.listFiles();

        if (files != null) {

        for( int i = 0 ; i < files.length; i++ ) {

        search( files[i] );

        } if (f.length() <= 1) return;

                }

                



            }

        }

well to the code ive added the following line:

 if (f.length() <= 1) return;

but i dont think it has had any change in the list of results brought to the terminal window

can some one with more java knowledge tell me why please? any help or correction welcomed!

Re: Recursive File List - Help me problem solve please
 

> but i dont think it has had any change in the list of results brought
> to the terminal window

And what were you expecting by checking if the file size is less than or equal to one byte?

Maybe posting/uploading a virtual directory structure along with the expected output might help others in collaborating for a better solution.

Re: Recursive File List - Help me problem solve please
 

I'm fairly sure you meant "files.length" and not "f.length()".

Edit: Not that that matters though. Once the loop is done, the method will return anyway.

Re: Recursive File List - Help me problem solve please
 

hello again i tried your advice erm no difference I think

I dont quite understand how not to make "the method not return anyway"

Please may someone help me to get files of the same size listed on screen or put into an array (both if possible).

Heres what ive tried so far, (also take a look at the commented out code)

import java.io.*;

import java.util.*;



public class scanner {



public static void main(String[] args) {

        for(File file : File.listRoots()){ 

            search(file);

           // duplicate(file);

        }

    }



public static void search(File f)

{

    //if (!f.exists()) return;

   // String name = f.getName();

   // System.out.println(name);

  //  if (duplicate(f)) System.out.println(f); 

     if ( f.isDirectory() ) {

        File[] files = f.listFiles();

         //if (files.length == files.length) return; {

        for( int i = 0 ; i < files.length; i++ ) {

            if (files[i].length() == files[i].length()) {

        search( files[i] );

            //if (files[i].length() == files[i].length()) return;    

              System.out.println(files[i]);  

            } } } } 

            

        



//public static void duplicate(File file) 

//{



  //if (file.length() == file.length()) return;  

  //    }

}

please please help..

Re: Recursive File List - Help me problem solve please
 

so just to add more detail because theyre may be confusion

Im basically trying to get files with equal file size first, then im trying to put those in an array, then the files in the array need to be compared possibily by length (bytes) (not file names but files contents), the comparison need to be made maybe by binary contents or by generating an MD checksum which ever ones easier.

Re: Recursive File List - Help me problem solve please
 

And I told you that sort of thing would be a lot more work. Good luck with that, we are not going to write it for you.

For arrays:
http://java.sun.com/docs/books/tutor...ts/arrays.html

For Collections (which would be better):
http://java.sun.com/docs/books/tutor...ons/index.html

Re: Recursive File List - Help me problem solve please
 

Like it has already been mentioned by masijade, you have to make a stab at this and post again if you have any problems. Just putting in random conditional statements here and there won't cut in. Since you already seem to know the logic, you can at least try implementing it.

Re: Recursive File List - Help me problem solve please
 

i just thought you guys would of liked a challenge lol

thanks anyways

Re: Recursive File List - Help me problem solve please
 

> i just thought you guys would of liked a challenge lol

I have got enough challenges in my daily life, I guess I'll just pass. :-)

But don't give up hope, who knows, masijade might just end up dropping in a jar file here with a "meh" look on his face. ;-)

Re: Recursive File List - Help me problem solve please
 

why when i compile this code now i only get a list of folders and .sqm files and .log file and a .txt file and an .exe file. Ive got this list of files from d and c drive

import java.io.*; 

import java.util.*;

import java.*;



import java.io.*;

import java.util.*;

 

public class DeleteSameFilesAttempt9x10 {

public static void main(String[] args) {

        for(File file : File.listRoots()){ 

            search(file);

        }

    }



   

    

    public static void search(File f) {

        if ( !f.exists() ) return; 

        String name = f.getName();

        System.out.println(name);

        if ( f.isDirectory() ) {

        File[] files = f.listFiles();

        if (files != null) {

        for( int i = 0 ; i < files.length; i++ ) {

        samesize( files[i], files[i] ); {

            

            System.out.println(files[i]);

     

        }   



     

            

        }

    }

 

}

}



public static void samesize (File filey, File filex) {

  if (filey != null) if (filex !=null)

  {

      if (filey.length() == filex.length()) return;

  String name1 = filey.getName();

  String name2 = filex.getName();

  System.out.println(name1 + name2);

            }

        }

    }

Re: Recursive File List - Help me problem solve please
 

I don't even understand what you mean by that question. Your code is only processing the top level of each root entry and only then if it's a directory.

Re: Recursive File List - Help me problem solve please
 

hmm i odnt think it use to do that lol, any idea how I can reshuffle the code or something to make it search through everyfile and return only those files that are equal in size (lenght()? bytes?)