Question

I was messing around with the java.io.File methods today, and stumbled on something kind of weird.

When I rename a directory, I can’t seem to ever delete the files or new directory.

    File dir = new File("dir");
    dir.mkdir();

    File file = new File(dir, "afile.txt");
    file.createNewFile();

    File newname = new File(dir, "newName.txt");
    file.renameTo(newname);

    File newdir = new File("newdir");
    dir.renameTo(newdir);

    System.out.println("file exists? " + file.exists());
    System.out.println("file deleted? " + file.delete());
    System.out.println("newname exists? " + newname.exists());
    System.out.println("deleted newname? " + newname.delete());
    System.out.println("dir exists? " + dir.exists());
    System.out.println("dir deleted? " + dir.delete());
    System.out.println("newdir exists? " + newdir.exists());
    System.out.println("deleted newdir? " + newdir.delete());

Yields the output:

    file exists? false
    file deleted? false
    newname exists? false
    deleted newname? false
    dir exists? false
    dir deleted? false
    newdir exists? true
    deleted newdir? false

In the filesystem, though, newdir and newname.txt both still exist!

However, if I comment out the renaming of the directory, the delete works fine.

Are there additional rules between delete() and rename() one needs to know about? There’s not much in the javadoc.

Answer 1

I don’t see any problem with the output:

1. At the end of the renaming, only newdir/ and newdir/newName.txt exist. Therefore the first six lines of output should be false, and they are. (In particular, the newname variable still refers to dir/newName.txt, which no longer exists.)

2. newdir does exist; your output confirms this.

3. The final delete() doesn’t work because the directory is not empty.

In summary, everything appears to work exactly as one would expect.