Rename a file using Java

Question

Can we rename a file say test.txt to test1.txt ?

If test1.txt exists will it rename ?

How do I rename it to the already existing test1.txt file so the new contents of test.txt are added to it for later use?

Solution 1

Copied from http://exampledepot.8waytrips.com/egs/java.io/RenameFile.html

// File (or directory) with old name
File file = new File("oldname");

// File (or directory) with new name
File file2 = new File("newname");

if (file2.exists())
   throw new java.io.IOException("file exists");

// Rename file (or directory)
boolean success = file.renameTo(file2);

if (!success) {
   // File was not successfully renamed
}

To append to the new file:

java.io.FileWriter out= new java.io.FileWriter(file2, true /*append=yes*/);

Solution 2

In short:

Files.move(source, source.resolveSibling("newname"));

More detail:

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardCopyOption;

The following is copied directly from http://docs.oracle.com/javase/7/docs/api/index.html:

Suppose we want to rename a file to "newname", keeping the file in the same directory:

Path source = Paths.get("path/here");
Files.move(source, source.resolveSibling("newname"));

Alternatively, suppose we want to move a file to new directory, keeping the same file name, and replacing any existing file of that name in the directory:

Path source = Paths.get("from/path");
Path newdir = Paths.get("to/path");
Files.move(source, newdir.resolve(source.getFileName()), StandardCopyOption.REPLACE_EXISTING);

Solution 3

You want to utilize the renameTo method on a File object.

First, create a File object to represent the destination. Check to see if that file exists. If it doesn't exist, create a new File object for the file to be moved. call the renameTo method on the file to be moved, and check the returned value from renameTo to see if the call was successful.

If you want to append the contents of one file to another, there are a number of writers available. Based on the extension, it sounds like it's plain text, so I would look at the FileWriter.

Solution 4

For Java 1.6 and lower, I believe the safest and cleanest API for this is Guava's Files.move.

Example:

File newFile = new File(oldFile.getParent(), "new-file-name.txt");
Files.move(oldFile.toPath(), newFile.toPath());

The first line makes sure that the location of the new file is the same directory, i.e. the parent directory of the old file.

EDIT: I wrote this before I started using Java 7, which introduced a very similar approach. So if you're using Java 7+, you should see and upvote kr37's answer.

Solution 5

Renaming the file by moving it to a new name. (FileUtils is from Apache Commons IO lib)

  String newFilePath = oldFile.getAbsolutePath().replace(oldFile.getName(), "") + newName;
  File newFile = new File(newFilePath);

  try {
    FileUtils.moveFile(oldFile, newFile);
  } catch (IOException e) {
    e.printStackTrace();
  }

View more solutions

Comments

[user207421]

Your last paragraph does not describe a rename operation at all. It describes an append operation.

[Thomas Owens]

No idea, but it's the exact same thing that Pierre posted, without the source code...

[Stephane Grenier]

This code won't work in all cases or platforms. The rename to method is not reliable: stackoverflow.com/questions/1000183/…

[Caelum]

Path is an interface whose only implementations are WindowsPath, ZipPath and AbstractPath. Will this be a problem for multi-platform implementations?

[maxivis]

Hi @user2104648, here (tutorials.jenkov.com/java-nio/path.html) is an example about how could you handle the files in Linux environment. Basically, you need to use java.nio.file.Paths.get(somePath) instead of using one of the implementations you've mentioned

[Koray Tugay]

What is Path source = ... ?

[Anh Pham]

Usually it's better to explain a solution instead of just posting some rows of anonymous code. You can read How do I write a good answer, and also Explaining entirely code-based answers

[Joel Klinghed]

Copy and rename are usually different operations so I think it should be clearly marked that this is a copy. Which also happens to be unnecessary slow as it copies characters and not bytes.

[andras]

Only the Path way is working for me, renameTo always returns false. Check either the answer of kr37 or this answer

[Gaurav]

@kr37 flawless answer!

[Forage]

How is this any different from the accepted answer given by Pierre 9 years earlier?

[yurin]

@KorayTugay. Path source = file.getAbsolutePath(); Where file is the file which needs to be renamed.

[Dmytro Moskovchenko]

For some reason, the file just disappears if I run it.

[JohnK]

This looks more like making a copy than renaming. What am I missing?