Записи (records) в Java

public final class FXOrderClassic {
    private final int units;
    private final CurrencyPair pair;
    private final Side side;
    private final double price;
    private final LocalDateTime sentAt;
    private final int ttl;

    public FXOrderClassic(int units, 
               CurrencyPair pair, 
               Side side, 
               double price, 
               LocalDateTime sentAt, 
               int ttl) {
        this.units = units;
        this.pair = pair; // CurrencyPair is a simple enum
        this.side = side; // Side is a simple enum
        this.price = price;
        this.sentAt = sentAt;
        this.ttl = ttl;
    }

    public int getUnits() {
        return units;
    }

    public CurrencyPair getPair() {
        return pair;
    }

    public Side getSide() {
        return side;
    }

    public double getPrice() { 
        return price;
    }

    public LocalDateTime getSentAt() {
        return sentAt;
    }

    public int getTtl() {
        return ttl;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) 
            return false;

        FXOrderClassic that = (FXOrderClassic) o;

        if (units != that.units) return false;
        if (Double.compare(that.price, price) != 0) 
            return false;
        if (ttl != that.ttl) return false;
        if (pair != that.pair) return false;
        if (side != that.side) return false;
        return sentAt != null ? 
            sentAt.equals(that.sentAt) : that.sentAt == null;
    }

    @Override
    public int hashCode() {
        int result;
        long temp;
        result = units;
        result = 31 * result + 
                   (pair != null ? pair.hashCode() : 0);
        result = 31 * result + 
                   (side != null ? side.hashCode() : 0);
        temp = Double.doubleToLongBits(price);
        result = 31 * result + 
                   (int) (temp ^ (temp >>> 32));
        result = 31 * result + 
                   (sentAt != null ? sentAt.hashCode() : 0);
        result = 31 * result + ttl;
        return result;
    }

    @Override
    public String toString() {
        return "FXOrderClassic{" +
                "units=" + units +
                ", pair=" + pair +
                ", side=" + side +
                ", price=" + price +
                ", sentAt=" + sentAt +
                ", ttl=" + ttl +
                '}';
    }
}

var order = new FXOrderClassic(1, 
                    CurrencyPair.GBPUSD, 
                    Side.Bid, 1.25, 
                    LocalDateTime.now(), 1000);

public record FXOrder(int units,
                      CurrencyPair pair,
                      Side side,
                      double price,
                      LocalDateTime sentAt,
                      int ttl) {}

javac --enable-preview -source 14 FXOrder.java

$ javap FXOrder.class
Compiled from "FXOrder.java"
public final class FXOrder extends java.lang.Record {
    public FXOrder(int, CurrencyPair, Side, double, 
        java.time.LocalDateTime, int);
    public java.lang.String toString();
    public final int hashCode();
    public final boolean equals(java.lang.Object);
    public int units();
    public CurrencyPair pair();
    public Side side();
    public double price();
    public java.time.LocalDateTime sentAt();
    public int ttl();
}

public final class FXOrderClassic extends Record {
    private final int units;
    private final CurrencyPair pair;
    private final Side side;
    private final double price;
    private final LocalDateTime sentAt;
    private final int ttl;
    
    // ... rest of class elided
}

R copy = new R(r.c1(), r.c2(), ..., r.cn());

jshell> var o = new Object() {
   ...>   public void bar() { System.out.println("bar!"); }
   ...> }
o ==> $0@37f8bb67

jshell> var o2 = new Object() {
   ...>   public void bar() { System.out.println("bar!"); }
   ...> }
o2 ==> $1@31cefde0

jshell> o = o2;
|  Error:
|  incompatible types: $1 cannot be converted to $0
|  o = o2;
|      ^^

record OrderPartition(CurrencyPair pair, Side side) {}

public record FXOrder(int units, 
                      CurrencyPair pair, 
                      Side side, 
                      double price, 
                      LocalDateTime sentAt, 
                      int ttl) {
    public FXOrder {
        if (units < 1) {
            throw new IllegalArgumentException(
                "FXOrder units must be positive");
        }
        if (ttl < 0) {
            throw new IllegalArgumentException(
                "FXOrder TTL must be positive, or 0 for market orders");
        }
        if (price <= 0.0) {
            throw new IllegalArgumentException(
                "FXOrder price must be positive");
        }
    }
}

public static FXOrder of(CurrencyPair pair, Side side, double price) {
        return new FXOrder(1, pair, side, price, 
                           LocalDateTime.now(), 1000);
}

record OrderPartition(CurrencyPair pair, Side side) {
    public OrderPartition(FXOrder order) {
        this(order.pair(), order.side());
    }
}

public final class MatchingEngine {
    private final Map<OrderPartition, RankedOrderBook> 
      orderBooks = new TreeMap<>();

    public void addOrder(final FXOrder o) {
        orderBooks.get(new OrderPartition(o)).addAndRank(o);
        checkForCrosses(o.pair());
    }

    public void checkForCrosses(final CurrencyPair pair) {
        // Do any buy orders match with sells now?
    }

    // ...
}