java file.renameTo() does rename file but returns false. Why?

Question

The problem is that I need the file to move before the rest of my logic will work so when the method returns false I stop execution.

However, when I check on the file in windows explorer it has a new name and it moved.

Just curious why this is happening.

here is some sample code I just tried to recreate the issue. It's pretty much the same thing and it's working fine.

File testfile = new File("TestFile");

    if(!testfile.exists()){

        testfile.mkdirs();

    }

    File sample = new File("sample.txt");

    if(sample.exists()){

        boolean success = sample.renameTo(new File(testfile.getPath() + "\\" + sample.getName()));

        if(success){

            System.out.println("Moved");

        }
        else{

            System.out.println("Failed");

        }

    }

Edit: Solved it. I'm sorry for wasting everyone's time with something so silly. However, I really dont think I would have tracked this down if not for making this post.

The solution was that I was actually looping through several files to move. When the output said it failed then the program stopped and when I looked in explorer only the first of the files was actually moved so I assumed it was moving and then returning false. However, the issue was that I was using the wrong variable as an index and so what was happeneing was that it did successfully move the file in index 0 and then when the loop repeated the index didnt increment so it tried to move index 0 again and therefore failed.

Like I said, very stupid but thanks for bearing with me.

Answer 1

Java's File.renameTo() is problematic, especially on Windows, it seems. As the API documentation says:

Many aspects of the behavior of this method are inherently platform-dependent: The rename operation might not be able to move a file from one filesystem to another, it might not be atomic, and it might not succeed if a file with the destination abstract pathname already exists. The return value should always be checked to make sure that the rename operation was successful.

You can use apache.commons.io library, which includes FileUtils.moveFile() or also the Files.move() method in JDK 7.

Answer 2

Isn't it possible that you file has a Inputstream open somewhere but has not been closed and so the rename is not working. Try closing all open streams relevant to the file object before closing.