Lesson 43: Basic File Handling: Reading and Writing Files

Java handles file operations using Input/Output (I/O) classes. We will focus on the modern approach introduced in Java 7: NIO.2 (java.nio.file).

1. The Path Interface

In NIO.2, the Path interface represents a file system path, making path manipulation cross-platform and easier.

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

// Create a Path object Path filePath = Paths.get("data", "info.txt"); System.out.println(filePath.toAbsolutePath());

2. Reading a File (Simplified)

The Files utility class provides simple static methods for common operations.

java import java.nio.file.Files; import java.nio.charset.StandardCharsets; import java.io.IOException; import java.util.List;

Path path = Paths.get("example.txt");

try { // Reads all lines into a List List lines = Files.readAllLines(path, StandardCharsets.UTF_8); for (String line : lines) { System.out.println(line); } } catch (IOException e) { System.err.println("File reading failed: " + e.getMessage()); }

3. Writing to a File (Simplified)

java import static java.nio.file.StandardOpenOption.CREATE; import static java.nio.file.StandardOpenOption.APPEND;

Path outputPath = Paths.get("output.log"); String content = "Log entry: " + LocalDateTime.now();

try { // Writes content, creating the file if necessary, and appending to it. Files.write(outputPath, content.getBytes(), CREATE, APPEND); } catch (IOException e) { e.printStackTrace(); }

Note: Traditional file operations use FileInputStream/FileOutputStream (byte streams) or FileReader/FileWriter (character streams). The NIO.2 Files class provides cleaner, high-level methods that often handle the stream management for you.