how to read files in a directory on a local network

[Nasim Salehi]

Hi all,
I need to read some folders from directory on machines inside a local network and copy them in another location,In fact I'm deploying some folders to a central location manually,
I'm wondering if I should use FileInputStream and something like this?
I tried this one and I can read files on my local machine,
here's the code I used for reading all filenames in a directory:

public void readFileList(String name)
{
//String name = "D:\\tools";
StringTokenizer toker;
File f1 = new File(name);
File[] list = f1.listFiles(); //Get all files in the directory "name"
String files = "", fname;
for(int i = 0; i<list.length; i ++){

fname=list[i].toString(); //Turn filename into a string
toker = new StringTokenizer(fname,"\\"); //parse out the path before the filename
while(toker.hasMoreTokens())
fname=toker.nextToken();
System.out.println("fname; "+ fname);
files = files + "\"" + fname.substring(0, fname.length()-4) + "\","; //parse out the extension ".jpg"
}
files = files.substring(0,files.length()-1);
System.out.println("files: "+files);
}

but when I want to read from a directory on another machine in local network I got this error:

Exception in thread "main" java.lang.NullPointerException
at com.irisaco.wfm.service.ReadFileListDir.readFileList(ReadFileListDir.java:15)
at com.irisaco.wfm.service.ReadFileListDir.main(ReadFileListDir.java:33)
 

Any help would be great.

[Stan James]

We can't tel just which line threw that error from here, but I'd guess it's because of this bit from the doc on File.listFiles(): Returns null if this abstract pathname does not denote a directory, or if an I/O error occurs.

What's the filename string you're passing to new File()?

[Nasim Salehi]

Thank you for your attention,
the string I've passed to the new file() method for reading from local network is something like this: "\\mycomputerName\folderName" which mycomputerName is name of my computer in network and folderName is name of the folder i want to read list of files in.I really have no idea if such addressing across a local network could be correct or there's another way?

[Rob Spoor]

Can the user that is running the program access this folder?

And in Java, do you specify it as follows: "\\\\mycomputerName\\folderName"? You'll need the 4 backslashes at the start, because \ is the Java escape character and \\ will indicate only a single backslash.

[Nasim Salehi]

Thanks a lot dear Rob!
It works!
I'd forgot the way java deals with backslashes.
Now,do you have any idea for copying files ?

[Ulf Dittmer]

The Jakarta Commons IO library has a number of useful routines for file copying in the IOUtils class. Might be easier to use those than to roll your own.

[Nasim Salehi]

I tried to use that as below:

public void copyfile(String srFile, String dtFile){
    try{
      File f1 = new File(srFile);
      File f2 = new File(dtFile);
      InputStream in = new FileInputStream(f1);
      
      //For Append the file.
//      OutputStream out = new FileOutputStream(f2,true);
 
      //For Overwrite the file.
      OutputStream out = new FileOutputStream(f2);
 
      byte[] buf = new byte[1024];
      int len;
      while ((len = in.read(buf)) > 0){
        out.write(buf, 0, len);
      }
      in.close();
      out.close();
      System.out.println("File copied.");
    }
    catch(FileNotFoundException ex){
      System.out.println(ex.getMessage() + " in the specified directory.");
      System.exit(0);
    }
    catch(IOException e){
      System.out.println(e.getMessage());      
    }
  }
  public static void main(String[] args){
  
  CopyFile cp = new CopyFile();
  cp.copyfile("D:\\temp", "D:\\Nasim");
}

I got this error:

D:\temp (Access is denied) in the specified directory.

Any idea?

[Rob Spoor]

You can only copy files this way, not folders.