Records

Definition

A record is a short way to declare a class that only carries data. You list the fields once, and Java creates the constructor, getters, equals, hashCode and toString. The fields are final.

Example code

A data class in one line

record Point(int x, int y) {
    double distanceFromOrigin() { return Math.sqrt(x * x + y * y); }   // records can have methods

    Point {                                                            // compact constructor: validation
        if (x < 0 || y < 0) throw new IllegalArgumentException("coordinates must be positive");
    }
}

class Demo {
    public static void main(String[] args) {
        Point p = new Point(3, 4);
        System.out.println(p);                          // toString is generated
        System.out.println(p.x() + ", " + p.y());       // accessors are generated
        System.out.println(p.equals(new Point(3, 4)));  // equals compares the values
        System.out.println(p.distanceFromOrigin());
    }
}

// Output:
// Point[x=3, y=4]
// 3, 4
// true
// 5.0