Java change file type

How to change file extension at runtime in Java

This is how I used to rename files or change its extension.

public static void modify(File file) < int index = file.getName().lastIndexOf("."); //print filename //System.out.println(file.getName().substring(0, index)); //print extension //System.out.println(file.getName().substring(index)); String ext = file.getName().substring(index); //use file.renameTo() to rename the file file.renameTo(new File("Newname"+ext)); >

edit: John’s method renames the file (keeping the extension). To change the extension do:

public static File changeExtension(File f, String newExtension)

This changes only the last extension to a filename, i.e. the .gz part of archive.tar.gz . Therefore it works fine with Linux hidden files, for which the name starts with a . This is quite safe because if getParent() returns null (i.e. in the event of the parent being the system root) it is «cast» to an empty String as the whole argument to the File constructor is evaluated first.

The only case where you will get a funny output is if you pass in a File representing the system root itself, in which case the null is prepended to the rest of the path string.

Solution 2

File file = new File("fileName.zip"); // handler to your ZIP file File file2 = new File("fileName.fileExtension"); // destination dir of your file boolean success = file.renameTo(file2); if (success) < // File has been renamed >

Solution 3

I would check, if the file has an extension before changing. The solution below works also with files without extension or multiple extensions

public File changeExtension(File file, String extension) < String filename = file.getName(); if (filename.contains(".")) < filename = filename.substring(0, filename.lastIndexOf('.')); >filename += "." + extension; file.renameTo(new File(file.getParentFile(), filename)); return file; > @Test public void test() < assertThat(changeExtension(new File("C:/a/aaa.bbb.ccc"), "txt"), is(new File("C:/a/aaa.bbb.txt"))); assertThat(changeExtension(new File("C:/a/test"), "txt"), is(new File("C:/a/test.txt"))); >

Solution 4

I want to avoid the new extension just happening to be in the path or filename itself. I like a combination of java.nio and apache StringFilenameUtils.

public void changeExtension(Path file, String extension) throws IOException

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How to change file extension at runtime in java?

If you need to change the file extension of a file in Java at runtime, there are a few different methods you can use. The most straightforward way to do this is to simply rename the file using the desired extension. In some cases, you may also need to modify the contents of the file to ensure it is in the proper format for the new extension. Here are a few different ways to change a file’s extension in Java:

Method 1: Rename the File

To change the file extension of a file in Java using the «Rename the File» method, you can follow these steps:

1. Create a File object with the path of the file you want to rename.
2. Use the renameTo() method to rename the file by passing a new File object with the new file name and extension as the argument.

import java.io.File; public class FileExtensionChanger  public static void main(String[] args)  // create a File object with the path of the file you want to rename File file = new File("path/to/file.txt"); // create a new File object with the new file name and extension File newName = new File("path/to/newfile.pdf"); // use the renameTo() method to rename the file boolean renamed = file.renameTo(newName); if (renamed)  System.out.println("File extension changed successfully."); > else  System.out.println("File extension could not be changed."); > > >

In this example, we create a File object with the path of the file we want to rename, and then create a new File object with the new file name and extension. Finally, we use the renameTo() method to rename the file and check if the operation was successful.

Note that the renameTo() method returns a boolean value indicating whether the file was successfully renamed or not.

This method is simple and straightforward, but it has some limitations. For example, it can only change the file extension, not the file name itself. Also, it may not work on all operating systems or file systems.

Method 2: Modify the File Contents

To change the file extension of a file at runtime in Java using the «Modify the File Contents» approach, you can follow these steps:

File file = new File("path/to/oldfile.txt");

File newFile = new File("path/to/newfile.pdf");

try (FileInputStream fis = new FileInputStream(file); FileOutputStream fos = new FileOutputStream(newFile))  byte[] buffer = new byte[1024]; int length; while ((length = fis.read(buffer)) > 0)  fos.write(buffer, 0, length); > >

import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class FileExtensionChanger  public static void main(String[] args) throws IOException  File file = new File("path/to/oldfile.txt"); File newFile = new File("path/to/newfile.pdf"); try (FileInputStream fis = new FileInputStream(file); FileOutputStream fos = new FileOutputStream(newFile))  byte[] buffer = new byte[1024]; int length; while ((length = fis.read(buffer)) > 0)  fos.write(buffer, 0, length); > > file.delete(); > >

This code will read the contents of «oldfile.txt» and write them to a new file named «newfile.pdf». The old file will then be deleted.

Method 3: Write a Custom Function to Handle the Extension Change

In order to change the file extension at runtime in Java, you can write a custom function to handle the extension change. Here is an example code snippet that demonstrates how to do this:

import java.io.File; public class ChangeFileExtensionExample  public static void main(String[] args)  File file = new File("example.txt"); String newExtension = ".docx"; changeFileExtension(file, newExtension); > public static void changeFileExtension(File file, String newExtension)  String fileName = file.getName(); int lastDotIndex = fileName.lastIndexOf("."); String newFileName = fileName.substring(0, lastDotIndex) + newExtension; File newFile = new File(file.getParent(), newFileName); boolean success = file.renameTo(newFile); if (!success)  System.out.println("Failed to change file extension."); > > >

In this example, we start by creating a File object that represents the file we want to change the extension of. We then specify the new extension we want to use (in this case, .docx ).

Next, we call our custom function changeFileExtension and pass in the file and new extension as arguments.

Inside the changeFileExtension function, we first get the name of the file and find the index of the last dot in the name (which indicates the start of the file extension). We then create a new file name by replacing the old extension with the new one.

Finally, we create a new File object with the new file name and parent directory, and call the renameTo method to actually change the file extension. If the rename operation is successful, the function will return true , otherwise it will return false .

That’s it! With this custom function, you can easily change the file extension of any file at runtime in Java.

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How to change file extension at runtime in Java

Solution: Try to split and take only the extension’s split: An example: BONUS — CLICK ME Question: I’m trying to trim the file extension in file system using this way: The solution below works also with files without extension or multiple extensions Solution 4: By the same logic as mentioned @hsz, but instead simply use replacement:

How to change file extension at runtime in Java

I am trying to implement program to zip and unzip a file. All I want to do is to zip a file (fileName.fileExtension) with name as fileName.zip and on unzipping change it again to fileName.fileExtension .

This is how I used to rename files or change its extension.

public static void modify(File file) < int index = file.getName().lastIndexOf("."); //print filename //System.out.println(file.getName().substring(0, index)); //print extension //System.out.println(file.getName().substring(index)); String ext = file.getName().substring(index); //use file.renameTo() to rename the file file.renameTo(new File("Newname"+ext)); >

edit : John’s method renames the file (keeping the extension). To change the extension do:

public static File changeExtension(File f, String newExtension)

This changes only the last extension to a filename, i.e. the .gz part of archive.tar.gz . Therefore it works fine with Linux hidden files, for which the name starts with a . This is quite safe because if getParent() returns null (i.e. in the event of the parent being the system root) it is «cast» to an empty String as the whole argument to the File constructor is evaluated first.

The only case where you will get a funny output is if you pass in a File representing the system root itself, in which case the null is prepended to the rest of the path string.

File file = new File("fileName.zip"); // handler to your ZIP file File file2 = new File("fileName.fileExtension"); // destination dir of your file boolean success = file.renameTo(file2); if (success) < // File has been renamed >

I would check, if the file has an extension before changing. The solution below works also with files without extension or multiple extensions

public File changeExtension(File file, String extension) < String filename = file.getName(); if (filename.contains(".")) < filename = filename.substring(0, filename.lastIndexOf('.')); >filename += "." + extension; file.renameTo(new File(file.getParentFile(), filename)); return file; > @Test public void test() < assertThat(changeExtension(new File("C:/a/aaa.bbb.ccc"), "txt"), is(new File("C:/a/aaa.bbb.txt"))); assertThat(changeExtension(new File("C:/a/test"), "txt"), is(new File("C:/a/test.txt"))); >

By the same logic as mentioned @hsz, but instead simply use replacement:

File file = new File("fileName.fileExtension"); // creating object of File String str = file.getPath().replace(".fileExtension", ".zip"); // replacing extension to another file.renameTo(new File(str)); 

Rename file to uppercase in the same directory using Java, I would first add a check, if this is Windows or Linux/Unix/Mac. If it’s Windows, there should be an intermediary step that renames the file to a temporary name (I would suggest using System.currentMillis() as a unique name) and then moving this file under the uppercase name. Otherwise, your code won’t work …

Rename the file while preserving file extension in java

How to rename a file by preserving file extension?

In my case I want to rename a file while uploading it. I am Using Apache commons FileUpload library.

File uploadedFile = new File(path + "/" + fileName); item.write(uploadedFile); //renaming uploaded file with unique value. String newName = new File(path + "/" + id); if(uploadedFile.renameTo(newName)) < >else

The above code is changing the file extension too. How can I preserve it? Is there any good way with apache commons file upload library?

Try to split and take only the extension’s split:

String[] fileNameSplits = fileName.split("\\."); // extension is assumed to be the last part int extensionIndex = fileNameSplits.length - 1; // add extension to id File newName = new File(path + "/" + id + "." + fileNameSplits[extensionIndex]); 

public static void main(String[] args) < String fileName = "filename.extension"; System.out.println("Old: " + fileName); String String[] fileNameSplits = fileName.split("\\."); // extension is assumed to be the last part int extensionIndex = fileNameSplits.length - 1; // add extension to id System.out.println("New: " + id + "." + fileNameSplits[extensionIndex]); >

How to atomically rename a file in Java, even if the dest, I have a cluster of machines, each running a Java app. These Java apps need to access a unique resource.txt file concurrently.. I need to atomically rename a temp.txt file to resource.txt in Java, even if resource.txt already exist.. Deleting resource.txt and renaming temp.txt doesn’t work, as it’s not atomic (it creates a …

Java: rename file in file system (trim the extension)

I’m trying to trim the file extension in file system using this way:

private void passingFileRename(File f) throws Exception

But it doesn’t work, I get the filename but renameTo method seems to be locked or something.. What I’m doing wrong?

please look at this question. It seems like Java’s file.renameTo(file) is quite problematic.

Delete and, I have the following Java code which will search in an xml for a specific tag and then will add some text to it and save that file. I couldnt find a way to rename the emporary file to the original file.

How to change the extension of a File using java?

I want to rename, or convert, a bunch of files with the extension m4a to mp3 files. I could just rename them all manually but I thought that it I could do it using java, so from things that I found from other peoples questions I wrote a program, i got a lot of errors when i tried different things so i edited it to remove the errors, and left it in a way that would hopefully be easy for someone to determine what I wanted and or trying to do. What did i do wrong? How do I fix it?

import java.io.File; public class FileConverter < File folder = new File("/Users/noah/Desktop/HeadphoneMusic/"); File[] listOfFiles = folder.listFiles(); String p; File f1,f2; public void convert()< for (int i=0; i> > public String newFileName(String name) < String newName=""; for(int i=0; inewName+="mp3"; return newName; > > public class Tester < public static void main(String[] args) < // TODO Auto-generated method stub FileConverter mp3 = new FileConverter(); mp3.convert(); >> 

import java.io.File; public class FileConverter < File folder = new File("/Users/noah/Desktop/HeadphoneMusic/"); File[] listOfFiles = folder.listFiles(); String oldFilename; File f1,f2; public void convert()< for (int i=0; i> > > public class Tester < public static void main(String[] args) < // TODO Auto-generated method stub FileConverter mp3 = new FileConverter(); mp3.convert(); >> 

but when I check the folder containing the files, nothing is changed. What did I do wrong?

Don’t overcomplicate things.

The new filename is trivially calculated with a regex:

String newFilename = oldFilename.replaceAll("\\.m4a$", ".mp3"); 

but you could also have done it like this:

String newFilename = oldFilename.substring(0, oldFilename.length() - 3) + "mp3"; 

which is similar to your method, but way more efficient. It also assumes that all of the files are m4a files, ending with .m4a ; that might be true, but it’s better not to assume, just in case you run the code on the wrong directory.

Also, File.getName() doesn’t give you enough of the path to construct a new File correctly. Use File.getParentFile() to get the directory containing the file, then use this to construct a File in the same directory as the original file:

File f1 = new File(listOfFiles[i].getParentFile(), newFilename); 

File — Java: splitting the filename into a base and, There are also .tar.bz2, .tar.xz, .tar.lz and .tar.lzma file «extensions» in use. But how would you decide, whether to split at the last dot, or the second-to-last dot? Use mime-types instead. The Java 7 function Files.probeContentType will likely be much more reliable to detect file types than trusting the file extension. …

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