Java Concurrency: `java.util.concurrent` package

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Questions and Answers

Which statement correctly describes the primary function of the `java.util.concurrent` package?

Provides classes for basic input and output operations.
Offers a set of utility classes for mathematical operations.
Supplies tools for creating graphical user interfaces.
Contains a set of interfaces and classes that facilitate concurrent programming in Java. (correct)

What is the main purpose of the `ExecutorService` interface in Java's concurrent programming?

To manage and control the execution of threads. (correct)
To provide functionalities for file management.
To define user interface components.
To handle database connections and transactions.

Which of the following is NOT a typical use case for concurrent programming?

Creating responsive user interfaces by performing long-running tasks in the background.
Developing a single-threaded application that performs calculations sequentially. (correct)
Parallelizing computationally intensive tasks to reduce execution time.
Handling multiple client requests in a server application.

What is the significance of the `volatile` keyword in Java concurrency?

It ensures that a variable's value is always read from and written to main memory, avoiding thread-local caches. (C) Signup and view all the answers

How does the `synchronized` keyword in Java help in managing concurrent access to shared resources?

By using locks to allow only one thread at a time to access a critical section of code, preventing race conditions. (B) Signup and view all the answers

Which of the following best describes the concept of a 'race condition' in concurrent programming?

A scenario where the outcome of a program depends on the unpredictable order of execution of multiple threads accessing shared resources. (D) Signup and view all the answers

What is the main difference between `ArrayList` and `Vector` in Java regarding thread safety?

<code>Vector</code> is thread-safe because its methods are synchronized, while <code>ArrayList</code> is not thread-safe. (D) Signup and view all the answers

What is a key advantage of using `ConcurrentHashMap` over `HashMap` in a multithreaded environment?

<code>ConcurrentHashMap</code> provides better performance due to its lock striping, allowing multiple threads to read and write different portions of the map concurrently. (C) Signup and view all the answers

How do the `Lock` interface and its implementations (e.g., `ReentrantLock`) enhance the capabilities of thread synchronization compared to the `synchronized` keyword?

<code>Lock</code> offers more flexible locking mechanisms, such as the ability to attempt a lock without blocking or to interrupt a thread waiting for a lock, which are not possible with <code>synchronized</code>. (D) Signup and view all the answers

When using `CountDownLatch` in Java concurrency, what does the `await()` method do?

It causes the current thread to wait until the counter of the <code>CountDownLatch</code> reaches zero. (C) Signup and view all the answers

Flashcards

Java Libraries

A collection of pre-written code that developers can reuse in their programs. They provide classes and methods for performing common tasks, saving time and effort.

Concurrent Programming

A programming paradigm that allows multiple tasks to run seemingly simultaneously. It improves performance by utilizing multiple cores and handling I/O-bound operations efficiently.

Object-Oriented Programming (OOP)

A programming paradigm based on objects, which contain data (attributes) and code (methods) to manipulate that data. Key principles include encapsulation, inheritance, and polymorphism.

Encapsulation

Bundling data (attributes) and methods that operate on the data within a class, hiding the internal implementation details from the outside world.