VirtualThreadCallableDemo.java

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class VirtualThreadCallableDemo {
    public static void main(String[] args) {
        // Use a virtual thread executor (Java 21+)
        try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) {
            List<Callable<String>> tasks = new ArrayList<>();

            for (int i = 1; i <= 5; i++) {
                int taskId = i;
                tasks.add(() -> {
                    String threadName = Thread.currentThread().threadName();
                    // Simulate work that can be done concurrently
                    Thread.sleep(500L * taskId);
                    return "Task " + taskId + " completed on " + threadName;
                });
            }

            try {
                List<Future<String>> futures = executor.invokeAll(tasks);

                for (Future<String> future : futures) {
                    try {
                        System.out.println(future.get());
                    } catch (ExecutionException e) {
                        System.err.println("Task execution failed: " + e.getCause());
                    }
                }
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                System.err.println("Execution interrupted");
            }
        }
    }
}