Name: rlT66838 Date: 07/16/97


Create an instance of a File:

File file = new File("C:\\"); // slash
String[] contents = file.list();

contents is null even if C:\ is not empty.

Try again:
File file = new File("C:"); // no slash
String[] contents = file.list();

now we get something!

Note:
works fine on NT with or without the trailing slash.

======================================================================
roger.lewis@Eng 1997-07-22

If a File object is created on a drive letter (e.g. "c:") without a trailing slash, getAbsolutePath( ) assumes that c: is a file in the current directory.
Note that the File object itself is correct, as it give a correct directory listing. When a trailing slash is used, everything works correctly, except the
directory listing (as documented in bug report 4065189).

import java.io.*;

public class DirTest {

   public static void main( String argv[] ) {

      File file = new File( "c:" );
      System.err.println( "file.getAbsolutePath( \"c:\" )=" + file.getAbsolutePath( ) );

   }
}

C:\Alex>java DirTest
file.getAbsolutePath( "c:" )=C:\Alex\c:

===============================================================================

max.spivak@Eng 1997-08-01

Here's is some additional cannon fodder. If I'm in c:\mspivak and
call getParent(), I get c:\. If I then do a list() on that, it will
fail on Win95. Yes, a workaround exists to not use the \, but
so much for platform independence and WORE!

The code is followed by the output:

import java.io.*;
public class dirlist {
    public static void main(String[] args) {
if (args.length != 1) {
System.out.println("usage: java dirlist dirname");
return;
}

System.out.println("testing directory: " + args[0]);
File dir = new File(args[0]);

if (dir.exists())
System.out.println(dir + " exists");
else
System.out.println(dir + " doest NOT exist");

if (dir.isDirectory())
System.out.println(dir + " is a directory");
else
System.out.println(dir + " is NOT directory");

if (dir.isFile())
System.out.println(dir + " is a file");
else
System.out.println(dir + " is NOT a file");

System.out.println("path = " + dir.getPath());
System.out.println("abs path = " + dir.getAbsolutePath());
try { System.out.println("can path = " + dir.getCanonicalPath());}
catch (IOException ex) {ex.printStackTrace();}
System.out.println("name = " + dir.getName());
System.out.println("parent = " + dir.getParent());

System.out.println("can read = " + dir.canRead());
System.out.println("can write = " + dir.canWrite());

String files[] = dir.list();
System.out.println("files = " + files);
System.out.println("length = " + files.length);

    }
}

Now the output:

F:\tmp>java dirlist c:
testing directory: c:
c: exists
c: is NOT directory
c: is NOT a file
path = c:
abs path = F:\tmp\c:
can path = F:\tmp\c:
name = c:
parent = null
can read = true
can write = true
files = [Ljava.lang.String;@1cc81a
length = 31

F:\tmp>java dirlist c:testing directory: c:c:\ exists
c:\ is a directory
c:\ is NOT a file
path = c:abs path = c:can path = c:name =
parent = null
can read = true
can write = true
files = null
java.lang.NullPointerException:
        at dirlist.main(dirlist.java:40)

F:\tmp>java dirlist c:\mspivak
testing directory: c:\mspivak
c:\mspivak exists
c:\mspivak is a directory
c:\mspivak is NOT a file
path = c:\mspivak
abs path = c:\mspivak
can path = c:\mspivak
name = mspivak
parent = c:can read = true
can write = true
files = [Ljava.lang.String;@1cc7bb
length = 3

F:\tmp>java dirlist c:\mspivaktesting directory: c:\mspivakc:\mspivak\ exists
c:\mspivak\ is a directory
c:\mspivak\ is NOT a file
path = c:\mspivakabs path = c:\mspivakcan path = c:\mspivak
name =
parent = c:\mspivak
can read = true
can write = true
files = [Ljava.lang.String;@1cc7bb
length = 3

Running this on WinNT gives the following output:

F:\tmp>java dirlist c:
testing directory: c:
c: exists
c: is NOT directory
c: is NOT a file
path = c:
abs path = F:\tmp\c:
can path = F:\tmp\c:
name = c:
parent = null
can read = true
can write = true
files = [Ljava.lang.String;@1ea81a
length = 31

F:\tmp>java dirlist c:testing directory: c:c:\ exists
c:\ is a directory
c:\ is NOT a file
path = c:abs path = c:can path = c:name =
parent = null
can read = true
can write = true
files = [Ljava.lang.String;@1ea813
length = 31

===============================================================================