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

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## Single Thread Environment

The name `ConcurrentModificationException` may sound related to *concurrency*, however, the exception can be thrown while a single thread operates on a map. In fact, `ConcurrentModificationException` isn't even part of the ` java.util.concurrent` package. The exception occurs when a map is modified at the same time (concurrently) any of its collection views (keys, values or entry pairs) is being traversed. The program below demonstrates the exception being thrown as the main thread traverses the map entries and also attempts to insert new entries.

If you are interviewing, consider buying our number#1 course for <a href="https://www.educative.io/courses/java-multithreading-for-senior-engineering-interviews?affiliate_id=5457430901161984" target="_blank">Java Multithreading Interviews</a>.

# Single Thread Environment

The name `ConcurrentModificationException` may sound related to *concurrency*, however, the exception can be thrown while a single thread operates on a map. In fact, `ConcurrentModificationException` isn't even part of the ` java.util.concurrent` package. The exception occurs when a map is modified at the same time (concurrently) any of its collection views (keys, values or entry pairs) is being traversed. The program below demonstrates the exception being thrown as the main thread traverses the map entries and also attempts to insert new entries.

This lesson explains why ConcurrentModificationExceptions occurs and how it can be avoided. 

ConcurrentModificationException

This lesson explains why ConcurrentModificationExceptions occurs and how it can be avoided.

The Basics

Multithreading in Java

Java's Memory Model

Interview Practice Problems

Bonus Questions

Beyond the Interview

Java Concurrency Reference

Revision & Quizzes

ConcurrentModificationException