A Java record is a special kind of class for a fixed set of data components. Declare those components in the record header and Java supplies the corresponding fields, accessors, canonical constructor, and value-oriented implementations of equals, hashCode, and toString. Records became a permanent Java feature in Java SE 16, after previews in Java 14 and 15.
What is a record in Java?
A record is a class form designed for transparent data aggregates: types whose declared components describe their state. Oracle’s Java SE 25 record guide describes records as a way to model plain data aggregates with less ceremony than ordinary classes.
For example, a rectangle can be declared with its two dimensions in the record header:
record Rectangle(double length, double width) { }This is still a class, not a struct with arbitrary fields. The header establishes the record’s component list and, in turn, its central state description and generated API.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
What does a Java record generate?
For each component, Java provides a private final field and a public accessor with the component’s name. It also provides a canonical constructor whose parameters correspond to the components, along with implementations of equals, hashCode, and toString.
new Rectangle(4.0, 2.0)invokes the canonical constructor.rectangle.length()andrectangle.width()are the generated accessors. They use the component names, not JavaBean-style names such asgetLength().- The default equality and hash code use the component values, for instances of the same record class.
- The default string representation includes component names and their representations.
These defaults are useful when the components are the intended state of the value. A record can explicitly implement generated methods when a deliberate alternative is necessary, but custom behavior should fit the type’s declared state model.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
How can a record validate or normalize its data?
Records can have constructors and methods; they are not limited to passive storage. A compact canonical constructor lets a record validate or normalize its parameters while Java handles assignment to the component fields:
record Person(String name, int age) {
Person {
if (age < 0) throw new IllegalArgumentException("age must be nonnegative");
}
}
var person = new Person("Ada", 36);
System.out.println(person.name());The example illustrates a generated accessor and validation. Records can also declare instance methods, static members, and nested types, and can implement interfaces. The Java Language Specification’s record rules describes the language constraints in detail.
Free tools Windows power users keep installed
One-click scans. No signup required.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
When were records added to Java?
Records were previewed in Java SE 14 and Java SE 15, then finalized in Java SE 16. Code targeting Java 16 or later can use records without enabling a preview feature. Whether a particular project can compile and run such code depends on its selected source and runtime releases, not merely the developer’s installed JDK. Oracle summarizes the release change in its Java SE 16 language changes.
Are Java records immutable?
Records have final component fields, so those fields cannot be reassigned after construction. That is shallow finality, not a guarantee of deep immutability: a final field that holds a reference can still refer to a mutable object, and that object may change. For effectively immutable data, use immutable component types or take appropriate defensive measures.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
What are the important limits of records?
- No class inheritance: a record is implicitly final, has
java.lang.Recordas its direct superclass, and cannot extend a chosen domain class. It can implement interfaces. - The components define the state shape: records suit types where the component list is the authoritative description of state. Choose an ordinary class when the design needs a different state model or extensible class hierarchy.
- Accessor conventions may matter: generated accessors are named after components. A library expecting JavaBean
getX()methods or particular bean-introspection behavior may not treat a record as expected; check that library’s requirements. - Serialization has special rules: deserialization uses the canonical constructor. Record serialization does not support the usual custom
writeObject,readObject,readObjectNoData,writeExternal, orreadExternalhooks. See Oracle’s Java SE 16 record guide and the Java Language Specification changes for records before relying on custom serialization behavior.
When should you choose a record instead of a class?
| Use a record when… | Prefer an ordinary class when… |
|---|---|
| The declared components are the intended state description, and value-oriented equality and generated accessors fit the API. | The object needs a state model that is not naturally represented by a fixed component list, or its identity and equality need a different design. |
| Final component fields are appropriate, with immutable components or suitable handling for mutable referenced values. | The design needs reassignment of fields or a different state-management approach. |
| The type does not need to extend a domain superclass and consumers can use component-named accessors. | The type must extend a class or consumers require JavaBean accessor conventions. |
| Record-specific serialization rules work for the application. | The design depends on custom serialization hooks that records do not support. |
| The project’s target Java release supports finalized records (Java SE 16 or later). | The project must target an earlier Java release that does not support records as a finalized feature. |
A record reduces repeated declaration work without making every data-bearing type a record. The deciding question is whether a fixed component list accurately expresses the type’s state and whether the language’s inheritance, accessor, equality, and serialization rules fit its callers.
Quick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minute
