How to test rename in Java

Question

Suppose I rename file A to file B. Now I would like to test it. I can test that B exists and A does not. However I need to make sure that B is actually renamed A. How can I do it in Java for both Linux and Windows.

Wouldn't you have to do some low level stuff with inodes? Beyond the scope of java. — Bathsheba, Oct 14 '13 at 13:43
Yes, inode is what I would like to check. However I am afraid I cannot do it in Java (in portable way). — Michael, Oct 14 '13 at 13:57

score 2 · Answer 1 · edited May 23 '17 at 10:25

2

Read the contents of file A.
Hash it.
Rename the file.
Read the contents of file B.
Hash it and compare that to the hash of file A.

edited May 23 '17 at 10:25

Community

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answered Oct 14 '13 at 13:43

Bill the Lizard

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Thank. What if A and B are _folders_ rather than files ? – Michael Oct 14 '13 at 13:58
@Michael In that case I'd [trust the boolean returned by File.renameTo(File)](http://stackoverflow.com/a/19361763/1288). – Bill the Lizard Oct 14 '13 at 14:00
Yes, but what if I need to test a function, which is supposed to invoke _renameTo_ ? I would like to make sure _renameTo_ is invoked. – Michael Oct 14 '13 at 14:02

score 1 · Answer 2 · edited May 23 '17 at 10:25

1

You could compare the MD5 checksum of the file before and after the rename.

See Getting a File's MD5 Checksum in Java

edited May 23 '17 at 10:25

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answered Oct 14 '13 at 13:46

Hurzelchen

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score 1 · Answer 3 · answered Oct 14 '13 at 13:48

1

Why don't you just trust the boolean returned by File.renameTo(File) which indicates if the renaming worked or not?

answered Oct 14 '13 at 13:48

jend

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score 1 · Answer 4 · answered Oct 14 '13 at 13:49

import java.io.File;

public class Main {
   public static void main(String[] args) {
      File oldName = new File("C:/java1.txt");
      File newName = new File("C:/java2.txt");
      if(oldName.renameTo(newName)) {
         System.out.println("renamed");
      } else {
         System.out.println("Error");
      }
   }
}

Now for confirmation you can store the file content in string for both the file like

 String contentOld = new Scanner(new File("java1.txt")).useDelimiter("\\Z").next();


String contentNew = new Scanner(new File("java2.txt")).useDelimiter("\\Z").next();

Now compair the both string and you will get the result

contentOld.equals(contentNew)

if both have same content it will return true

score 0 · Answer 5 · answered Oct 14 '13 at 13:54

It is simple

if(B.exists()) throw new java.io.IOException("file already exists");

boolean success = A.renameTo(B);
if (success) {
   // File is successfully renamed.
}

But this way is platform dependent as API mentions : http://docs.oracle.com/javase/7/docs/api/java/io/File.html#renameTo%28java.io.File%29

Instead you can use

Files.move()

in platform independent manner , this throws relevant exceptions for you to check whether the file is really renamed or not. If the method returns the path to the target file, it has been renamed correctly, otherwise it will throw an exception. You can refer the link.

http://docs.oracle.com/javase/7/docs/api/java/nio/file/Files.html#move%28java.nio.file.Path,%20java.nio.file.Path,%20java.nio.file.CopyOption...%29

How to test rename in Java

5 Answers5