What are Java Records?

Records in Java (3 part series)

1. What are Java Records?
2. How to use Java Records
3. Java Records as Data Transfer Objects (upcoming)

Records have been in Java since version 16, but what are they and what can you use them for?

Records can be thought of as a replacement for simple data-holding POJOs.
These holders usually have one or more of the following properties:

• They are defined solely by the data they hold
• They have an equals() and hashCode() method based solely on their data
• Their fields are private and final, and they define a getter method for them
• They are written to and read from another format, like JSON or the database

Here is an example of such a POJO:

final class Customer {
  private final UUID id;
  private final String name;

  public Customer(UUID id, String name) {
    this.id = id;
    this.name = name;
  }

  public UUID getId() {
    return id;
  }

  public String getName() {
    return name;
  }

  @Override
  public String toString() {
    return "Customer[id=" + id + ", name=" + name + "]";
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    Customer customer = (Customer) o;
    return id.equals(customer.id) && name.equals(customer.name);
  }

  @Override
  public int hashCode() {
    return Objects.hash(id, name);
  }
}

Now let’s see the equivalent record implementation:

record Customer(String id, String name) {}

Need we say more? You can now stop reading and start using records everywhere,
or you can continue on to Part 2: how you use Java Records.