Complete Java Records Tutorial

This Java Records tutorial is part of the full crash course published over on TheServerSide. Check it out!

If you want to learn how to make your code less verbose, while also faster and more efficient at the same time, this Java Records tutorial is for you.

We'll cover all the most important Java 17 Records features and show you all the rules about how to use Java records. (By the way, Java records were previewed in Java 14 and released in Java 16, but Java 17 was the first LTS release to include them, so they are often called Java 17 records.

We'll also provide a bunch of Java records examples and even show you the Java records builder pattern. We'll talk about the Java record class, Java record setter and getter methods, Java record inheritance and how Java records work with interfaces.

If you need a Java records crash course, this tutorial is for you.

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Prompt: Explain what a Java record is, why Java records are important, how they improve performance and why developers should use them.

In Java, a record is a new type of class introduced in Java 14 as a preview feature and officially released in Java 16. Records provide a concise way to declare immutable data-carrying classes. They are similar to traditional Java classes but are primarily used to model data rather than behavior. A record class is declared using the record keyword followed by the class name and a list of components, which are essentially the fields of the record.

Here's a basic example of a Java record:

public record Person(String name, int age) {}

In this example, Person is a record class with two components: name of type String and age of type int. Records automatically generate several methods such as constructors, equals(), hashCode(), and toString() based on the components defined within them. These methods are often boilerplate in traditional Java classes but are generated automatically by the compiler for records.

Java records are important for several reasons:

Conciseness and Readability: Records reduce boilerplate code, making the codebase more concise and readable. They allow developers to focus on the data being modeled rather than the implementation details.

Immutable Data: Records are inherently immutable, meaning their state cannot be changed once initialized. This immutability helps in writing more predictable and thread-safe code.

Auto-generated Methods: Records automatically generate methods such as constructors, equals(), hashCode(), and toString(), reducing the need for manual implementation and potential sources of errors.

Pattern Matching: While not directly tied to records, the introduction of records in Java paved the way for pattern matching features introduced in later versions (starting from Java 16), which can improve code readability and maintainability.

Regarding performance, records themselves don't directly impact performance in terms of execution speed. However, their immutability and the generated equals() and hashCode() methods can lead to more efficient code when used in scenarios where comparisons and hashing are frequent, such as in collections like HashMap or HashSet.

Developers should use records when they need to model simple immutable data transfer objects (DTOs), value types, or entities without behavior. They can significantly reduce boilerplate code, improve code readability, and contribute to writing more maintainable and efficient Java code.

[manuelvalls]

thanks a lot for your explanation!! Really usefull!!

[pravinprince]

Thank you for the wonderful video sir, it is so helpful for me and my team, thanks sir

[smnomad]

Good video! Although I'd like to advise you to release more Mojo content and even create a full course on it. It will very rapidly become massive in the AI space, faster than people realize. I think there's an opportunity for you to grow this channel, especially since you're a great teacher by nature and your teaching style is perfect for a new language that programmers of all levels will discover. You could become the reference for Mojo on YouTube. Also, please invest in a better camera and monitor with higher resolution. The video quality is pretty bad, and the text on the monitor is not very clear. Other than that, your content is great!

[mils]

Thanks for the video, well explained.

Just a small addition, when you were explaining how to write a custom constructor and when you mentioned calling this(...) to the canonical constructor, that call MUST be defined on the first line of the constructor, not as you said somewhere in the constructor, implying that it can be defined later.
BR

[cameronmcnz]

Complete article is now available on TSS:

[scrumtuous]

What does Mario Lemieux have to do with Java? 🤣