The only guide you’ll need on concurrency & multithreading for senior engineers. Pressure test your skills with real-world practice problems from top companies.

Concurrency in Java is one of the most complex and advanced topics brought up during senior engineering interviews. Knowledge of concurrency and multithreading can put interviewees at a considerable advantage. This course lays the foundations of advanced concurrency and multithreading and explains concepts such as Monitors and Deferred Callbacks in depth. It also builds simple and complete solutions to popular concurrency problems that can be asked about in interviews like the Reader-Writer Problem and the Dining Philosopher Problem. While prior knowledge of concurrency is not required to follow through with this course, familiarity with the very basics of concurrency would be helpful.

Java Multithreading for Senior Engineering Interviews

# Taxonomy of atomic classes
There are a total of sixteen atomic classes divided into four groups:

1. Scalars
2. Field updaters
3. Arrays
4. Compound variables

Most well-known and commonly used are the scalar ones such as `AtomicInteger`, `AtomicLong`, `AtomicReference`, which support the CAS (compare-and-set). Other primitive types such as double and float can be simulated by casting `short` or `byte` values to and from `int` and using methods `floatToIntBits()` and `doubleToLongBits()` for floating point numbers. Atomic scalar classes extend from `Number` and don’t redefine `hashCode()` or `equals()`. 

# Atomics are not primitvies
The following widget highlights these differences between `Integer` and `AtomicInteger`. Note, that the `Integer` class has the same hashcode for the same integer value but that’s not the case for `AtomicInteger`. Thus `Atomic*` scalar classes are unsuitable as keys for collections that rely on hashcode.


Learn about the different categories of atomic classes and their performance in comparison to locks.

The Basics

Multithreading in Java

Java's Memory Model

Interview Practice Problems

Bonus Questions

Beyond the Interview

Java Concurrency Reference

Revision & Quizzes

More on Atomics

Taxonomy of atomic classes