Working with Path Objects and the NIO.2 API in Java

1. Creating and Using Path Objects

The NIO.2 API introduced the Path interface to work with file and directory paths in an abstract manner. Path instances are created using the Paths factory class.

Example: Creating a Path Object

import java.nio.file.Path;
import java.nio.file.Paths;

Path path = Paths.get("example.txt");
System.out.println("Path: " + path);
System.out.println("File name: " + path.getFileName());
System.out.println("Parent: " + path.getParent());

2. Interacting with Path Objects Using the Files API

The Files helper class provides methods for performing operations on files and directories represented by Path objects.

Example: Creating, Copying, and Deleting Files

import java.nio.file.*;

Path source = Paths.get("source.txt");
Path target = Paths.get("target.txt");

// Create a file
Files.createFile(source);
System.out.println("File created: " + source);

// Copy a file
Files.copy(source, target, StandardCopyOption.REPLACE_EXISTING);
System.out.println("File copied to: " + target);

// Delete a file
Files.delete(target);
System.out.println("File deleted: " + target);

3. Reading and Updating File Attributes

The NIO.2 API includes BasicFileAttributes and BasicFileAttributeView to retrieve and update file attributes efficiently.

Example: Reading File Attributes

import java.nio.file.*;
import java.nio.file.attribute.*;

Path path = Paths.get("example.txt");
BasicFileAttributes attributes = Files.readAttributes(path, BasicFileAttributes.class);

System.out.println("Creation Time: " + attributes.creationTime());
System.out.println("Size: " + attributes.size());

Example: Updating File Attributes

BasicFileAttributeView view = Files.getFileAttributeView(path, BasicFileAttributeView.class);
FileTime newTime = FileTime.fromMillis(System.currentTimeMillis());
view.setTimes(newTime, newTime, newTime);
System.out.println("File attributes updated.");

4. Reading Files Using Lambda Expressions

The NIO.2 API supports reading file data using lambda expressions and Streams for efficient, lazy processing.

Example: Traversing a Directory with Files.walk()

Files.walk(Paths.get(".")).forEach(System.out::println);

Example: Finding Files with Files.find()

Files.find(Paths.get("."), Integer.MAX_VALUE, 
    (path, attr) -> path.toString().endsWith(".txt"))
    .forEach(System.out::println);

Example: Listing Directory Contents with Files.list()

Files.list(Paths.get(".")).forEach(System.out::println);

Example: Reading File Lines with Files.lines()

Files.lines(Paths.get("example.txt"))
     .filter(line -> line.contains("Java"))
     .forEach(System.out::println);

Conclusion

The NIO.2 API provides powerful tools for managing file paths, performing file operations, retrieving/updating file attributes, and processing file data efficiently using Streams and lambda expressions. By mastering these tools, developers can write modern and efficient file-handling code.