Java Community | Help. Code. Learn.•12mo ago

Week 53 — What is `java.nio.file.Files` and how does it simplify I/O?

Question of the Week #53

What is java.nio.file.Files and how does it simplify I/O?

4 Replies

The Files class provides many convenience methods for accessing files. For example, it's possible to copy or move files:

Files.copy(Path.of("source.txt"),Path.of("target.txt"));//copies source.txt to target.txt
Files.move(Path.of("source.txt"),Path.of("target2.txt"));//moves source.txt to target2.txt
Files.delete(Path.of("target2.txt"));//deletes the target2.txt file

Files.copy(Path.of("source.txt"),Path.of("target.txt"));//copies source.txt to target.txt
Files.move(Path.of("source.txt"),Path.of("target2.txt"));//moves source.txt to target2.txt
Files.delete(Path.of("target2.txt"));//deletes the target2.txt file

Aside from dealing with existing files, it is also possible to create new files and directories:

Files.createFile(Path.of("someFile.txt"));
Files.createDirectory(Path.of("someDirectory"));
Files.createDirectories(Path.of("parentDirectory/childDirectory"));//also creates parent directories if needed

Files.createFile(Path.of("someFile.txt"));
Files.createDirectory(Path.of("someDirectory"));
Files.createDirectories(Path.of("parentDirectory/childDirectory"));//also creates parent directories if needed

Creating temporary directories and files at some platform-specific location and getting their path is also possible. The names of these directories/files is randomized but it is possible to set a prefix (and suffix for files).

Path tempDirectory = Files.createTempDirectory("myapplication-");//creates a temporary directory starting with myapplication- somewhere
Path tempFile = Files.createTempFile("myapplication-",".txt");//creates a temporary file starting with myapplication- and ending with .txt somewhere

Path tempDirectory = Files.createTempDirectory("myapplication-");//creates a temporary directory starting with myapplication- somewhere
Path tempFile = Files.createTempFile("myapplication-",".txt");//creates a temporary file starting with myapplication- and ending with .txt somewhere

Eric McIntyre•12mo ago

There are also methods for reading from/writing to files:

Files.write(Path.of("someFile.raw"), new byte[]{13, 37});
Files.write(Path.of("someFile.txt"), List.of("Hello", "World","","This is written into someFile.txt"), StandardCharsets.UTF_8);

byte[] contentAsByteArray = Files.readAllBytes(Path.of("someFIle.raw"));
String contentAsString = Files.readString(Path.of("someFile.txt"), StandardCharsets.UTF_8);
List<String> contentAsStringListSplitByLines = Files.readAllLines(Path.of("someFile.txt"), StandardCharsets.UTF_8);

Files.write(Path.of("someFile.raw"), new byte[]{13, 37});
Files.write(Path.of("someFile.txt"), List.of("Hello", "World","","This is written into someFile.txt"), StandardCharsets.UTF_8);

byte[] contentAsByteArray = Files.readAllBytes(Path.of("someFIle.raw"));
String contentAsString = Files.readString(Path.of("someFile.txt"), StandardCharsets.UTF_8);
List<String> contentAsStringListSplitByLines = Files.readAllLines(Path.of("someFile.txt"), StandardCharsets.UTF_8);

It is also possible to use a Stream for iterating over the lines of a file:

try(Stream<String> lines = Files.lines(Path.of("someFile.txt"), StandardCharsets.UTF_8)){
  List<String> linesStartingWithLetter = lines
    .filter(line -> !line.isEmpty())
    .filter(line -> Character.isLetter(line.charAt(0)))
    .toList();
  System.out.println(linesStartingWithLetter);
}

try(Stream<String> lines = Files.lines(Path.of("someFile.txt"), StandardCharsets.UTF_8)){
  List<String> linesStartingWithLetter = lines
    .filter(line -> !line.isEmpty())
    .filter(line -> Character.isLetter(line.charAt(0)))
    .toList();
  System.out.println(linesStartingWithLetter);
}

📖 Sample answer from dan1st

Eric McIntyre•12mo ago

With java.nio.file.Files, you can achieve file manipulation tasks with concise code and handle I/O operations efficiently, often reducing the need for boilerplate code when dealing with files and directories.

Submission from ig.imanish

Eric McIntyre•12mo ago

It is used for networking and file handling API it is an alternative to IO, it simplifies as it's easier to work with buffers and also can do non blocking io.

Submission from PNJ3.0#1519

Gaming

Programming

Week 53 — What is `java.nio.file.Files` and how does it simplify I/O?