Apache Commons-IO FileUtils in Java

The handling files with FileUtils from Apache Commons-IO in Java. The Apache Foundation has created a number of very useful data and file manipulation tools.

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Remember that when creating our examples we use Maven and in the POM file we add this dependency.

<dependency>
   <groupId>commons-io</groupId>
   <artifactId>commons-io</artifactId>
   <version>2.6</version>
</dependency>

The FileUtils class of the Commons-IO library will allow you to manipulate files in various ways, for example, to copy a file from one folder to another it is only necessary to use the copyFileToDirectory function. In this example we have a text file and we want to make a copy of it to the folder “subfolder”.

package com.geekole; // Name of your java package

import java.io.File;
import org.apache.commons.io.FileUtils;

/**
 *
 * @author geekole.com
 */
public class CopyFilesCommonsIO {

    public static void main(String args[]) {
        try {
            File file1 = new File("/home/geekole/Documents/java/files/file1.txt");
            File subfolder = new File("/home/geekole/Documents/java/files/subfolder/");
            FileUtils.copyFileToDirectory(file1, subfolder);
            System.out.println("Ready");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

If we run the example we get this result:

Only the file “file1.txt” is copied to the folder: /home/geekole/Documents/java/files/subfolder

Another very useful method is to copy the contents of one folder to another copyToDirectory.

package com.geekole; // Name of your java package

import java.io.File;
import org.apache.commons.io.FileUtils;

/**
 *
 * @author geekole.com
 */
public class CopyFoldersCommonsIO {

    public static void main(String args[]) {
        try {
            File sourceDirectory= new File("/home/geekole/Documents/java/files");
            File destinationDirectory = new File("/home/geekole/Documents/java/backupFiles");
            FileUtils.copyToDirectory(sourceDirectory, destinationDirectory);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

With the following result:

Copying the contents of /home/geekole/Documents/java/files recursively to /home/geekole/Documents/java/backupFiles/

FileUtils functions are especially useful:

String readFileToString(File file, Charset encoding) – Allows you to read the content of a text file and directly create a String.

public static void writeStringToFile(File file, String data, Charset encoding) – Allows you to create a text file with the content of a String that is passed as an argument along with its encoding.

But besides these simple examples, Apache Commons-IO FileUtils in Java has other methods that can help you:

• static String byteCountToDisplaySize(BigInteger size)
• static String byteCountToDisplaySize(long size)
• static Checksum checksum(File file, Checksum checksum)
• static long checksumCRC32(File file)
• static void cleanDirectory(File directory)
• static boolean contentEquals(File file1, File file2)
• static boolean contentEqualsIgnoreEOL(File file1, File file2, String charsetName)
• static File[] convertFileCollectionToFileArray(Collection<File> files)
• static void copyDirectory(File srcDir, File destDir)
• static void copyDirectory(File srcDir, File destDir, boolean preserveFileDate)
• static void copyDirectory(File srcDir, File destDir, FileFilter filter)
• static void copyDirectory(File srcDir, File destDir, FileFilter filter, boolean preserveFileDate)
• static void copyDirectoryToDirectory(File srcDir, File destDir)
• static void copyFile(File srcFile, File destFile)
• static void copyFile(File srcFile, File destFile, boolean preserveFileDate)
• static long copyFile(File input, OutputStream output)
• static void copyFileToDirectory(File srcFile, File destDir)
• static void copyFileToDirectory(File srcFile, File destDir, boolean preserveFileDate)
• static void copyInputStreamToFile(InputStream source, File destination)
• static void copyToFile(InputStream source, File destination)
• static void copyURLToFile(URL source, File destination)
• static void copyURLToFile(URL source, File destination, int connectionTimeout, int readTimeout)
• static void deleteDirectory(File directory)
• static boolean deleteQuietly(File file)
• static boolean directoryContains(File directory, File child)
• static void forceDelete(File file)
• static void forceDeleteOnExit(File file)
• static void forceMkdir(File directory)
• static void forceMkdirParent(File file)
• static File getFile(File directory, String… names)
• static File getFile(String… names)
• static File getTempDirectory()
• static String getTempDirectoryPath()
• static File getUserDirectory()
• static String getUserDirectoryPath()
• static boolean isFileNewer(File file, Date date)
• static boolean isFileNewer(File file, File reference)
• static boolean isFileNewer(File file, long timeMillis)
• static boolean isFileOlder(File file, Date date)
• static boolean isFileOlder(File file, File reference)
• static boolean isFileOlder(File file, long timeMillis)
• static boolean isSymlink(File file)
• static Iterator<File> iterateFiles(File directory, IOFileFilter fileFilter, IOFileFilter dirFilter)
• static Iterator<File> iterateFiles(File directory, String[] extensions, boolean recursive)
• static Iterator<File> iterateFilesAndDirs(File directory, IOFileFilter fileFilter, IOFileFilter dirFilter)
• static LineIterator lineIterator(File file)
• static LineIterator lineIterator(File file, String encoding)
• static Collection<File> listFiles(File directory, String[] extensions, boolean recursive)
• static Collection<File> listFilesAndDirs(File directory, IOFileFilter fileFilter, IOFileFilter dirFilter)
• static void moveDirectory(File srcDir, File destDir)
• static void moveDirectoryToDirectory(File src, File destDir, boolean createDestDir)
• static void moveFile(File srcFile, File destFile)
• static void moveFileToDirectory(File srcFile, File destDir, boolean createDestDir)
• static void moveToDirectory(File src, File destDir, boolean createDestDir)
• static FileInputStream openInputStream(File file)
• static FileOutputStream openOutputStream(File file)
• static FileOutputStream openOutputStream(File file, boolean append)
• static byte[] readFileToByteArray(File file)
• static String readFileToString(File file)
• static String readFileToString(File file, Charset encoding)
• static String readFileToString(File file, String encoding)
• static List<String> readLines(File file)
• static List<String> readLines(File file, Charset encoding)
• static List<String> readLines(File file, String encoding)
• static long sizeOf(File file)
• static BigInteger sizeOfAsBigInteger(File file)
• static long sizeOfDirectory(File directory)
• static BigInteger sizeOfDirectoryAsBigInteger(File directory)
• static File toFile(URL url)
• static File[] toFiles(URL[] urls)
• static void touch(File file)
• static URL[] toURLs(File[] files)
• static boolean waitFor(File file, int seconds)
• static void write(File file, CharSequence data)
• static void write(File file, CharSequence data, boolean append)
• static void write(File file, CharSequence data, Charset encoding)
• static void write(File file, CharSequence data, Charset encoding, boolean append)
• static void write(File file, CharSequence data, String encoding)
• static void write(File file, CharSequence data, String encoding, boolean append)
• static void writeByteArrayToFile(File file, byte[] data)
• static void writeByteArrayToFile(File file, byte[] data, boolean append)
• static void writeByteArrayToFile(File file, byte[] data, int off, int len)
• static void writeByteArrayToFile(File file, byte[] data, int off, int len, boolean append)
• static void writeLines(File file, Collection<?> lines)
• static void writeLines(File file, Collection<?> lines, boolean append)
• static void writeLines(File file, Collection<?> lines, String lineEnding)
• static void writeLines(File file, Collection<?> lines, String lineEnding, boolean append)
• static void writeLines(File file, String encoding, Collection<?> lines)
• static void writeLines(File file, String encoding, Collection<?> lines, boolean append)
• static void writeLines(File file, String encoding, Collection<?> lines, String lineEnding)
• static void writeLines(File file, String encoding, Collection<?> lines, String lineEnding, boolean append)
• static void writeStringToFile(File file, String data)
• static void writeStringToFile(File file, String data, boolean append)
• static void writeStringToFile(File file, String data, Charset encoding)
• static void writeStringToFile(File file, String data, Charset encoding, boolean append)
• static void writeStringToFile(File file, String data, String encoding)static void writeStringToFile(File file, String data, String encoding, boolean append)

We’ll be adding more examples of other Apache Commons-IO FileUtils in Java functions soon.