StructuredConcurrencyDemo.java

package java19.structuredconcurrency;

/**
 * Java 19 Structured Concurrency (Incubator) Demonstrates structured task scopes for concurrent programming
 * NOTE: Requires: - --add-modules jdk.incubator.concurrent - --enable-preview
 * Compile: javac --add-modules jdk.incubator.concurrent --enable-preview --release 19 StructuredConcurrencyDemo.java Run: java --add-modules jdk.incubator.concurrent --enable-preview StructuredConcurrencyDemo
 */
public class StructuredConcurrencyDemo
{
	public static void main(String[] args)
	{
		System.out.println("=== Java 19 Structured Concurrency (Incubator) ===\n");

		System.out.println("Structured Concurrency provides:");
		System.out.println("1. StructuredTaskScope - groups related tasks");
		System.out.println("2. Automatic cancellation on failure");
		System.out.println("3. Better error handling");
		System.out.println("4. Improved observability");

		System.out.println("\nExample usage:");
		System.out.println("""
				import jdk.incubator.concurrent.StructuredTaskScope;
				
				// ShutdownOnFailure - cancels all if any fails
				try (var scope = new StructuredTaskScope.ShutdownOnFailure()) {
				    Future<String> user = scope.fork(() -> fetchUser());
				    Future<String> order = scope.fork(() -> fetchOrder());
				
				    scope.join();  // Wait for all tasks
				    scope.throwIfFailed();  // Throw if any failed
				
				    // Use results
				    String userResult = user.resultNow();
				    String orderResult = order.resultNow();
				}
				// Automatic cleanup if any task fails
				""");

		System.out.println("\nKey Features:");
		System.out.println("- Automatic cancellation of subtasks");
		System.out.println("- Exception propagation");
		System.out.println("- Better error handling");
		System.out.println("- Structured lifecycle");
		System.out.println("- Improved observability");

		System.out.println("\nUse Cases:");
		System.out.println("- Parallel API calls");
		System.out.println("- Concurrent data fetching");
		System.out.println("- Task coordination");
		System.out.println("- Error handling in concurrent code");

		System.out.println("\nBenefits:");
		System.out.println("- Treats groups of tasks as a unit");
		System.out.println("- Automatic cleanup on failure");
		System.out.println("- Better error handling");
		System.out.println("- Structured lifecycle management");
	}

	// Example methods (would be implemented in real usage)
	private static String fetchUser()
	{
		// Simulate fetching user data
		return "User data";
	}

	private static String fetchOrder()
	{
		// Simulate fetching order data
		return "Order data";
	}
}