AsynchronousFileChannel (Async I/O)

AsynchronousFileChannel (Async I/O)

AsynchronousFileChannel allows for non-blocking reading and writing of files, enabling applications to perform I/O without stalling the main execution thread.

How it Works

Operations can be performed using either a Future (polling) or a CompletionHandler (callback). This is part of the Asynchronous I/O (AIO) features in Java 7.

Java Example

import java.nio.*;
import java.nio.channels.*;
import java.nio.file.*;
import java.util.concurrent.Future;

public class AsyncFileExample {
    public static void main(String[] args) throws Exception {
        Path path = Paths.get("test.txt");
        AsynchronousFileChannel channel = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
        ByteBuffer buffer = ByteBuffer.allocate(1024);
        Future<Integer> operation = channel.read(buffer, 0);
        while (!operation.isDone()) { /* do other things */ }
        System.out.println("Read complete: " + operation.get() + " bytes");
    }
}

Output

Read complete: 1024 bytes

Key Points

• Non-blocking file operations
• Supports Future and Callback models
• Improves scalability for I/O heavy apps
• Part of NIO.2 (JSR 203)