Great, you're **one step closer** to **becoming a Java developer**, as today you've **completed another section**. 

Maps are a **very useful data structure** that allows you to **store values in a key-value** structure. This way, you can **store data in an organized manner** with fast **access by key**. Additionally, with the help of `HashMap`, you **implemented an online store**, which is **quite good practice**. 

You're doing a **fantastic job**, and by moving forward at the same pace, you'll **achieve unprecedented success** in backend programming!

Now, a **small quiz** is prepared for you to recall the basic things you've learned in this section:


What is the average time complexity for basic operations (insertion, deletion, and retrieval) in a `HashMap`?

Which of the following interfaces does `HashMap` implement in Java?

Elevate your Java expertise with our Intermediate Data Structures course. Explore the dynamic world of ArrayLists, LinkedLists, Stacks, Queues, and more, unraveling their power and versatility.

In this section, you will be introduced to the concept of a list and the most commonly used types of lists. You will learn how to create them and use various lists correctly.

This section will introduce you to data structures that are not used as frequently but are still valuable. Data structures like set, stack, queue, and deque will help you better understand how Java works and various applications with databases. There will also be plenty of practice to reinforce both new and previous material.


This section will introduce you to a data structure called a map. This data structure operates on the principle of key-value pairs, meaning we retrieve data based on a specific key. This allows us to build various data structures that closely resemble databases. You will also learn about concepts such as HashCode and explore data structures like HashMap and HashSet.

The final touches on mastering the basic data structures. In this section, we will talk about another data structure - enum, and also explore how to work with the flow of information in the data structure using the Stream API.


Java Data Structures

Section 3 Summary

1. What is a `HashMap` in Java?

2. What is the average time complexity for basic operations (insertion, deletion, and retrieval) in a `HashMap`?

3. How does `HashMap` handle collisions?

4. Which of the following interfaces does `HashMap` implement in Java?

Java Data Structures

Section 3 Summary

1. What is a HashMap in Java?

2. What is the average time complexity for basic operations (insertion, deletion, and retrieval) in a HashMap?

3. How does HashMap handle collisions?

4. Which of the following interfaces does HashMap implement in Java?

1. What is a `HashMap` in Java?

2. What is the average time complexity for basic operations (insertion, deletion, and retrieval) in a `HashMap`?

3. How does `HashMap` handle collisions?

4. Which of the following interfaces does `HashMap` implement in Java?