Author Archives: Stanislav_Panteleev

💡 The constructor: is one of the most powerful and fine-tuned ways to create a HashMap. Let’s break down what each parameter means:

Excellent question, Stanley! Let’s break it down: How many new objects are created when you do map.put(key, value) in a HashMap? It depends on a few factors like resizing, collisions, and whether the key already exists. But in the most … Continue reading →

We’ll define a transition as a significant operation or decision point the HashMap makes to retrieve a value. This includes hashing, indexing, and comparisons.

If HashMap converts a bucket’s linked list to a red-black tree, how can that work when keys don’t necessarily implement Comparable? After all, a red-black tree needs to order keys to compare them — so how does that not break?

🚀 TL;DR: The worst-case runtime of get(key) when the key is in the map is: O(n) in Java versions before 8 (linked list buckets), O(log n) in Java 8 and later, thanks to treeified buckets, O(1) in the average case … Continue reading →

It depends on the internal structure of the HashMap and how collisions are handled.

🧠 What is the maximum number of hashCode() values? In Java, the return type of hashCode() is an int, so: That means: It returns a 32-bit signed integer. The range of values is:

The methods equals() and hashCode() play a critical role in how HashMap works under the hood. Let’s break it down with a clear and intuitive explanation. 🧠 🔧 How HashMap stores and finds keys: When you do: Step 1: Use … Continue reading →

Using byte[] as a key in a HashMapdoesn’t work the way you might expect — and it’s all because of how arrays handle equals() and hashCode() in Java. 🚫 Why byte[] doesn’t work as a HashMap key: 1. Default equals() … Continue reading →

⚠️ 1. Poor equals() and hashCode() implementation If you create your own key class and don’t override equals() and hashCode() properly, HashMap won’t be able to: Find existing entries correctly, Prevent duplicate keys, Replace values correctly. 🔥 Example: ➡️ Both … Continue reading →