Java Programming for Complete Beginners - Java 16 - Step 12 - Executor Service - Waiting for Completion of Multiple Task

This video tutorial explains how to execute multiple callable tasks using the executor service in Java. It covers creating callable tasks, using the future object to handle results, and managing multiple tasks with the invokeAll method. The tutorial also discusses handling exceptions and optimizing task execution with thread pools. By the end, viewers will understand how to efficiently manage concurrent tasks in Java.

What is the role of a 'future' in the context of callable tasks?

• It is a way to cancel tasks before execution.

• It is a tool to manage task priorities.

• It is a placeholder for a result that will be available later.

• It is a method to execute tasks immediately.

Why is it important to shut down the executor service?

• To allow the submission of new tasks.

• To ensure all tasks are completed before the program exits.

• To prevent memory leaks by stopping all threads immediately.

• To increase the speed of task execution.

What does the 'invokeAll' method do?

• Executes tasks sequentially and returns a single result.

• Executes all tasks and returns a list of futures.

• Cancels all tasks that are currently running.

• Executes tasks in a random order.

How can you handle exceptions when using 'invokeAll'?

• By logging them to a file.

• By ignoring them and continuing execution.

• By using a try-catch block around the 'invokeAll' call.

• By using a separate thread to handle exceptions.

What is the benefit of using a fixed thread pool with multiple threads?

• It reduces the number of tasks that can be executed.

• It limits the number of tasks that can be submitted.

• It allows tasks to be executed faster by using multiple threads.

• It ensures tasks are executed in a specific order.

What happens when you increase the number of threads in a thread pool?

• The tasks are executed more quickly.

• The tasks are executed more slowly.

• The tasks are executed in a random order.

• The tasks take longer to execute.

What is a good practice when experimenting with executor services?

• Avoid using executor services for small tasks.

• Only use a single thread to avoid complexity.

• Always use the maximum number of threads available.

• Try different numbers of tasks and threads to see the effects.