StructuredConcurrency.java

package java24.structuredconcurrency;


/**
 * Java 24 Structured Concurrency (Finalized) Demonstrates treating groups of tasks as a unit
 * NOTE: This feature is now finalized - no preview flag needed!
 */
public class StructuredConcurrency
{
	public static void main(String[] args)
	{
		System.out.println("=== Java 24 Structured Concurrency (Finalized) ===\n");

		System.out.println("Overview:");
		System.out.println("--------");
		System.out.println("Structured Concurrency treats groups of related tasks as a single unit,");
		System.out.println("ensuring proper lifecycle management and error handling.");
		System.out.println("This feature is now finalized in Java 24.\n");

		System.out.println("Example code structure:");
		System.out.println("""
				import java.util.concurrent.StructuredTaskScope;
				import java.util.concurrent.Future;
				
				public class StructuredConcurrency {
				    public static void main(String[] args) {
				        // 1. Basic structured concurrency
				        try (var scope = new StructuredTaskScope.ShutdownOnFailure<>()) {
				            Future<String> user = scope.fork(() -> fetchUser("123"));
				            Future<String> order = scope.fork(() -> fetchOrder("456"));
				            
				            scope.join();
				            scope.throwIfFailed();
				            
				            System.out.println("User: " + user.resultNow());
				            System.out.println("Order: " + order.resultNow());
				        } catch (Exception e) {
				            System.err.println("Error: " + e.getMessage());
				        }
				        
				        // 2. Shutdown on success
				        try (var scope = new StructuredTaskScope.ShutdownOnSuccess<String>()) {
				            scope.fork(() -> fetchUser("789"));
				            scope.fork(() -> fetchUser("999"));
				            
				            String result = scope.join().result();
				            System.out.println("First successful result: " + result);
				        } catch (Exception e) {
				            System.err.println("Error: " + e.getMessage());
				        }
				    }
				}
				""");

		System.out.println("\nKey Features:");
		System.out.println("- Structured lifecycle: Tasks are managed as a unit");
		System.out.println("- Error propagation: Failures are properly handled");
		System.out.println("- Shutdown strategies: ShutdownOnFailure and ShutdownOnSuccess");
		System.out.println("- Automatic cleanup: Resources are cleaned up automatically");
		System.out.println("- Prevents thread leaks: All tasks complete before scope closes");
		System.out.println("- Finalized feature (no preview flag needed)");

		System.out.println("\nBenefits:");
		System.out.println("- Better error handling");
		System.out.println("- Prevents thread leaks");
		System.out.println("- Clearer code structure");
		System.out.println("- Easier debugging");
		System.out.println("- Automatic resource management");
		System.out.println("- Production-ready (finalized)");

		System.out.println("\nNote: This feature is finalized in Java 24.");
		System.out.println("No --enable-preview flag needed!");
	}
}