File.copy() or File.move() – How to fix java.nio.file.FileAlreadyExistsException: /Users/app/robots.txt?

Are you getting java.nio.file.FileAlreadyExistsException error?

java.nio.file.FileAlreadyExistsException: /Users/app/Download/robots_files_copy.txt
	at java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:94)
	at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:106)
	at java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:111)
	at java.base/sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:218)
	at java.base/java.nio.file.spi.FileSystemProvider.newOutputStream(FileSystemProvider.java:478)
	at java.base/java.nio.file.Files.newOutputStream(Files.java:224)
	at java.base/java.nio.file.Files.copy(Files.java:3144)
	at crunchify.com.tutorial.CrunchifyDownloadFileFromURL.crunchifyFileDownloadUsingFilesCopy(CrunchifyDownloadFileFromURL.java:124)
	at crunchify.com.tutorial.CrunchifyDownloadFileFromURL.main(CrunchifyDownloadFileFromURL.java:40)

On Crunchify, we have more than 700 Java tutorials and 500+ WordPress tutorials. While running few Java programs today, I suddenly started getting above error from one of my Java class.

Here is my code:

	// Method-4: File Download using Files.copy()
	private static void crunchifyFileDownloadUsingFilesCopy(String crunchifyURL, String crunchifyFileLocalPath) {
		
		// URI Creates a URI by parsing the given string.
		// This convenience factory method works as if by invoking the URI(String) constructor;
		// any URISyntaxException thrown by the constructor is caught and wrapped in a new IllegalArgumentException object, which is then thrown.
		try (InputStream crunchifyInputStream = URI.create(crunchifyURL).toURL().openStream()) {
			
			// Files: This class consists exclusively of static methods that operate on files, directories, or other types of files.
			// copy() Copies all bytes from an input stream to a file. On return, the input stream will be at end of stream.
			
			// Paths: This class consists exclusively of static methods that return a Path by converting a path string or URI.
			// Paths.get() Converts a path string, or a sequence of strings that when joined form a path string, to a Path.
			Files.copy(crunchifyInputStream, Paths.get(crunchifyFileLocalPath));
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

In order to fix above error I had to replace one line with extra parameter StandardCopyOption.REPLACE_EXISTING.

Before:

Files.copy(crunchifyInputStream, Paths.get(crunchifyFileLocalPath));

After:

Files.copy(crunchifyInputStream, Paths.get(crunchifyFileLocalPath), StandardCopyOption.REPLACE_EXISTING);

REPLACE_EXISTING replaces an existing file if it exists.

That’s it. Now you won’t get above error any more. This step works for File.move() operation too.