Tip #60: Understanding Records in Java

Records, introduced in JDK 14 as a preview and finalized in JDK 16, are a new kind of class designed to model immutable data. They provide a concise syntax for creating data-centric classes with less boilerplate code. A Record is essentially a transparent carrier for data and automatically generates essential methods like toString(), hashCode(), and equals(), which are typically manually written in traditional classes.

Using Records can significantly reduce the verbosity of your code when you only need a data container with immutable fields. For example, instead of writing a full class with getters, setters, and a constructor, a Record provides an elegant solution with the same features and additional benefits, such as built-in immutability and better JVM optimizations for final fields.

Example:

Traditional Class:

public class Car {
    private String make;
    private String model;
    private int year;
    private String color;

    public Car(String make, String model, int year, String color) {
        this.make = make;
        this.model = model;
        this.year = year;
        this.color = color;
    }

    public String getMake() {
        return make;
    }

    public String getModel() {
        return model;
    }

    public int getYear() {
        return year;
    }

    public String getColor() {
        return color;
    }
}

Record Equivalent:

public record Car(String make, String model, int year, String color) { }

As you can see, a Record automatically generates all the necessary methods, including the constructor, accessors (make(), model(), etc.), and overrides for toString(), hashCode(), and equals() without you needing to write them manually. This makes your code simpler, more readable, and less error-prone.

Records are ideal when you’re working with data that doesn’t need to be changed after construction—immutable and lightweight!

Stay tuned, as we’ll dive deeper into advanced use cases and nuances of Records in upcoming tips. There's a lot more to explore!

Happy coding!