Java on Yonatan Karp-Rudin

[Interview Questions] Concurrency vs. Parallelism: Decoding the Simultaneous Illusion

Sat, 11 Mar 2023 00:00:00 +0100

TL;DR - What are the differences between concurrent and parallel programming?

One of my most successful posts so far is a detailed explanation of my favorite interview question (see How does HashMap work in Java? for more details). As a result, I’ve decided to create a series of posts breaking down more questions. All the questions that will be answered during this series have been used in my current employer’s hiring process.

How does HashMap work in Java?

Fri, 02 Dec 2022 00:00:00 +0100

As an interviewer, I often ask the question about how HashMap works in Java. It helps me assess a candidate’s understanding of data structures, JVM internals, and their problem-solving approach. I’ve encountered many candidates, including juniors, mid-levels, and seniors, who couldn’t answer this question correctly. So, I decided to share the answer with everyone.

In this article, I will explain the HashMap question step by step.

What is the contract between the equals() and hashCode() functions in Java?

How to Break Your HashMap in Less Than a Minute

Fri, 02 Dec 2022 00:00:00 +0100

TL;DR: Never use mutable objects as keys in your HashMap!

After I wrote my article How does HashMap work in Java?, a few people suggested more topics related to HashMap. As a result, I decided to create a short series of articles about it.

In today’s article, we will discuss JVM HashMaps and how they can be easily broken if not used carefully. It’s important to note that while we’ll be focusing on the JVM world, the same principles apply to most modern programming languages.