Fileutils Java

FileUtils is a class in the Apache Commons IO library for Java that provides various methods for working with files and directories. The library provides an easy-to-use API for developers to perform common file and directory operations such as copying, deleting, moving, reading, writing, and comparing files.Some of the most commonly used methods in the FileUtils class include:

• copyFile() - Copies a file from one location to another.
• copyDirectory() - Copies a directory and its contents to a new location.
• moveFile() - Moves a file from one location to another.
• moveDirectory() - Moves a directory and its contents to a new location.
• deleteQuietly() - Deletes a file or directory without throwing an exception if it fails.
• forceDelete() - Deletes a file or directory and throws an exception if it fails.
• forceMkdir() - Creates a directory and its parents if they don't already exist.
• readFileToString() - Reads the contents of a file into a string.
• writeStringToFile() - Writes a string to a file.

1. copyFile():

The copyFile() method copies a file from one location to another. Here's an example of how to use it:

File source = new File("C:\\myFolder\\file.txt");
File dest = new File("C:\\myFolder\\newFile.txt");
FileUtils.copyFile(source, dest);

In this example, we're copying the file "file.txt" from the "C:\myFolder" directory to a new file called "newFile.txt" in the same directory.

2. copyDirectory():

The copyDirectory() method copies a directory and its contents to a new location. Here's an example:

File sourceDir = new File("C:\\myFolder");
File destDir = new File("C:\\newFolder");
FileUtils.copyDirectory(sourceDir, destDir);

This code will copy the entire "myFolder" directory to a new directory called "newFolder".

3. deleteQuietly():

The deleteQuietly() method deletes a file or directory without throwing an exception if it fails. Here's an example:

File file = new File("C:\\myFolder\\file.txt");
FileUtils.deleteQuietly(file);

This code will delete the file "file.txt" from the "myFolder" directory. If the file doesn't exist or the deletion fails, no exception will be thrown.

4. forceDelete():

The forceDelete() method deletes a file or directory and throws an exception if it fails. Here's an example:

File file = new File("C:\\myFolder\\file.txt");
FileUtils.forceDelete(file);

This code will delete the file "file.txt" from the "myFolder" directory. If the deletion fails, an exception will be thrown.

5. moveFile():

The moveFile() method moves a file from one location to another. Here's an example:

File source = new File("C:\\myFolder\\file.txt");
File dest = new File("C:\\myFolder\\newFile.txt");
FileUtils.moveFile(source, dest);

This code will move the file "file.txt" from the "myFolder" directory to a new file called "newFile.txt" in the same directory.

6. moveDirectory():

The moveDirectory() method moves a directory and its contents to a new location. Here's an example:

File sourceDir = new File("C:\\myFolder");
File destDir = new File("C:\\newFolder");
FileUtils.moveDirectory(sourceDir, destDir);

This code will move the entire "myFolder" directory to a new directory called "newFolder".

7. forceMkdir():

The forceMkdir() method creates a directory and its parents if they don't already exist. Here's an example:

File dir = new File("C:\\newFolder\\subfolder");
FileUtils.forceMkdir(dir);

This code will create a new directory called "subfolder" inside the "newFolder" directory. If the "newFolder" directory doesn't exist, it will be created as well.

8. readFileToString():

The readFileToString() method reads the contents of a file into a string. Here's an example:

File file = new File("C:\\myFolder\\file.txt");
String contents = FileUtils.readFileToString(file, "UTF-8");

This code will read the contents of the file "file.txt" into a string called "contents", assuming that the file is encoded using the UTF-8 character set.

9. writeStringToFile():

The writeStringToFile() method writes a string to a file. Here's an example:

File file = new File("C:\\myFolder\\file.txt");
String contents = "Hello, world!";
FileUtils.writeStringToFile(file, contents, "UTF-8");

This code will write the string "Hello, world!" to the file "file.txt", assuming that the file is encoded using the UTF-8-character set.

10. listFiles():

The listFiles() method returns an array of File objects for all the files in a directory. Here's an example:

File dir = new File("C:\\myFolder");
File[] files = FileUtils.listFiles(dir, null, false);

This code will get an array of File objects for all the files in the "myFolder" directory. The second argument is an optional FileFilter that can be used to filter the files returned, and the third argument specifies whether to include subdirectories in the search.

11. sizeOf():

The sizeOf() method returns the size of a file or directory. Here's an example:

File file = new File("C:\\myFolder\\file.txt");
long size = FileUtils.sizeOf(file);

This code will get the size of the file "file.txt" in bytes.

12. checksum():

The checksum() method calculates the checksum of a file using a specified algorithm. Here's an example:

File file = new File("C:\\myFolder\\file.txt");
String checksum = FileUtils.checksum(file, "SHA-256");

This code will calculate the SHA-256 checksum of the file "file.txt" and return it as a string.

13. forceDeleteOnExit():

The forceDeleteOnExit() method schedules a file or directory to be deleted when the JVM exits. Here's an example:

File file = new File("C:\\myFolder\\file.txt");
FileUtils.forceDeleteOnExit(file);

This code will schedule the file "file.txt" to be deleted when the JVM exits.

14. touch():

The touch() method creates a new empty file or updates the last modified time of an existing file. Here's an example:

File file = new File("C:\\myFolder\\file.txt");
FileUtils.touch(file);

This code will create a new empty file called "file.txt" in the "myFolder" directory, or update the last modified time of the file if it already exists.

15. copyInputStreamToFile():

The copyInputStreamToFile() method copies the contents of an InputStream to a file. Here's an example:

InputStream input = new FileInputStream("C:\\input.txt");
File output = new File("C:\\output.txt");
FileUtils.copyInputStreamToFile(input, output);

This code will copy the contents of the "input.txt" file to a new file called "output.txt" in the same directory.

16. deleteDirectory():

The deleteDirectory() method deletes a directory and all its contents recursively. Here's an example:

File dir = new File("C:\\myFolder");
FileUtils.deleteDirectory(dir);

This code will delete the "myFolder" directory and all its contents. In addition to these methods, the FileUtils class also provides methods for working with directories, comparing files, and finding files. Overall, the FileUtils class provides an easy-to-use API for performing common file and directory operations in Java. Some of the features are:

• One of the most useful features of FileUtils is the ability to work with directories. The FileUtils class provides methods for creating, deleting, and copying directories. The createDirectory method is used to create a new directory, while the deleteDirectory method is used to delete an existing directory.
• Another useful feature of FileUtils is the ability to compare files. The contentEquals method is used to compare the contents of two files. This method returns true if the contents of both files are equal, and false otherwise. The FileUtils class also provides methods for finding files. The listFiles method is used to get a list of all the files in a directory. This method can also be used with a filter to get a list of files that match a certain pattern.
• FileUtils class in Java provides a wide range of useful methods for working with files and directories. Its easy-to-use API and comprehensive feature set make it a valuable tool for developers working with file I/O in Java.
• FileUtils can be used to perform atomic file operations. This means that if an error occurs during the operation, the file will be left in its original state. This is achieved using the TempFileUtils class, which creates a temporary file to store the new contents of the file. Once the new contents have been written to the temporary file, the original file is deleted and the temporary file is renamed to the original file name.
• FileUtils can be used to set the last modified time of a file using the setLastModified method. This can be useful when working with files that need to be updated periodically, such as log files.
• FileUtils provides methods for working with file permissions. The chmod method is used to change the permissions of a file, while the canRead, canWrite, and canExecute methods are used to check the permissions of a file.
• FileUtils can be used to read and write binary files using the readByteArrayToFile and writeByteArrayToFile methods. These methods are useful when working with image files or other types of binary data.
• The FileUtils class provides methods for handling exceptions that may occur during file operations. These methods include the handleIOException method, which can be used to log or handle IOExceptions, and the swallowIOException method, which is used to ignore IOExceptions.
• Overall, FileUtils is a powerful and flexible class that provides a wide range of features for working with files and directories in Java. Its comprehensive API and robust exception handling make it a valuable tool for developers working with file I/O in Java.