Records

// Traditional class — ~30 lines
public final class Point {
    private final int x;
    private final int y;
    // constructor, getters, equals, hashCode, toString ...
}

// Record — 1 line
record Point(int x, int y) {}

Point p = new Point(3, 4);
p.x();          // 3 — accessor
p.y();          // 4
p.toString();   // Point[x=3, y=4]

record User(String name, String email) {
    // Compact constructor — runs before all components are assigned
    User {
        Objects.requireNonNull(name, "name required");
        email = email.toLowerCase(); // normalize
    }

    // Custom methods are allowed
    public boolean isPremium() {
        return email.endsWith("@company.com");
    }
}

@RestController
public class UserController {

    record UserResponse(String id, String name, String email) {}

    @GetMapping("/users/{id}")
    public UserResponse getUser(@PathVariable String id) {
        return new UserResponse(id, "Alice", "alice@example.com");
    }
}

record Pair(int row, int col) {} // as a HashMap key
Map<Pair, Integer> visited = new HashMap<>();
visited.put(new Pair(0, 0), 0);