Executor Framework

The Executor Framework simplifies thread management by using thread pools.

Why Use Executors?

Creating threads manually is expensive. Thread pools reuse threads for better performance.

Core Interfaces

Executor

Executor executor = Executors.newFixedThreadPool(3);
executor.execute(() -> System.out.println("Task executed"));

ExecutorService

Extends Executor with lifecycle management.

ExecutorService service = Executors.newFixedThreadPool(5);
service.submit(() -> {
    System.out.println("Task running");
});
service.shutdown(); // Graceful shutdown

Types of Thread Pools

Callable and Future

Callable returns a result (unlike Runnable).

Callable<Integer> task = () -> {
    return 42;
};

ExecutorService service = Executors.newSingleThreadExecutor();
Future<Integer> future = service.submit(task);
Integer result = future.get(); // Blocks until result is ready

Quiz