Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.nio.file.*;
import java.util.List;
import java.util.stream.Collectors;

public class ReadingFilesDemo {

public static void main(String[] args) throws IOException {
        Path path = Path.of("sample.txt");

// Create a sample file to read
        Files.writeString(path, "Line 1: Hello
Line 2: World
Line 3: Java IO
");

// --- Files.readAllLines (loads all into memory) ---
        List<String> lines = Files.readAllLines(path, StandardCharsets.UTF_8);
        System.out.println("readAllLines (" + lines.size() + " lines):");
        lines.forEach(l -> System.out.println("  " + l));

// --- Files.readString ---
        String content = Files.readString(path, StandardCharsets.UTF_8);
        System.out.println("
readString length: " + content.length());

// --- BufferedReader (good for large files) ---
        System.out.println("
BufferedReader:");
        try (BufferedReader reader =
                Files.newBufferedReader(path, StandardCharsets.UTF_8)) {
            String line;
            int lineNum = 1;
            while ((line = reader.readLine()) != null) {
                System.out.printf("  %2d: %s%n", lineNum++, line);
            }
        }

// --- Files.lines() + Stream API ---
        System.out.println("
Files.lines() + stream:");
        try (var stream = Files.lines(path, StandardCharsets.UTF_8)) {
            List<String> filtered = stream
                .filter(l -> l.contains("Java"))
                .collect(Collectors.toList());
            System.out.println("Lines containing 'Java': " + filtered);
        }

Files.deleteIfExists(path); // cleanup
    }
}