syntax = "proto3";

package car;

option java_multiple_files = true;
option java_package = "com.example.car";
option java_outer_classname = "CarProto";

// Определение сообщений
message Car {
  string model = 1;
  int32 year = 2;
  CarStatus status = 3;
}

// Перечисление (enum)
enum CarStatus {
  ACTIVE = 0;
  INACTIVE = 1;
}

// Определение сервиса
service CarService {
  rpc BuyCar (CarRequest) returns (CarResponse);
}

message CarRequest {
  string model = 1;
}

message CarResponse {
  string confirmation = 1;
}

syntax = "proto3";

package car;

option java_package = "com.example.car";
option java_multiple_files = true;
option java_outer_classname = "CarProto";

message User {
  string name = 1;
  int32 age = 2;
  repeated string hobbies = 3;
}


string name = 1; — поле с типом string и номером 1.

int32 age = 2; — целочисленное поле.

repeated string hobbies = 3; — массив строк.

Важно: номер поля (= 1, = 2, = 3) — это не просто индекс. Это ключ в бинарной сериализации, который должен быть уникален и неизменен.

enum CarStatus {
  ACTIVE = 0;
  INACTIVE = 1;
  SOLD = 2;
}

service CarService {
  rpc BuyCar (CarRequest) returns (CarResponse);
  rpc ListCars (Empty) returns (CarList);
}

message Garage {
  map<string, Car> cars = 1;
}

message Car {
  string model = 1;
  int32 year = 2;
}

message Car {
  string model = 1;
  reserved 2;             // резервируем номер
  reserved "status_old";  // резервируем имя
}

message User {
  string name = 1;
  int32 age = 2;
}

message User {
  string name = 1;
  reserved 2;
  string email = 3;
}

protoc \
  --java_out=./build/generated \
  --grpc-java_out=./build/generated \
  proto/car.proto

syntax = "proto3";

service CarService {
  rpc BuyCar (CarRequest) returns (CarResponse);
}

message CarRequest {
  string model = 1;
  int32 budget = 2;
}

message CarResponse {
  string message = 1;
}

// Отправитель (клиент)
CarRequest request = CarRequest.newBuilder()
    .setModel("BMW")
    .setBudget(20000)
    .build();

CarResponse response = stub.buyCar(request);
System.out.println(response.getMessage());

public class CarServiceImpl extends CarServiceGrpc.CarServiceImplBase {
    @Override
    public void buyCar(CarRequest request, StreamObserver<CarResponse> responseObserver) {
        String msg = "Car purchased: " + request.getModel();
        CarResponse response = CarResponse.newBuilder().setMessage(msg).build();

        responseObserver.onNext(response);
        responseObserver.onCompleted();
    }
}

import java.util.Optional;

public class Task011125 {
    public static void main(String[] args) {
        Optional<String> opt1 = Optional.ofNullable(null);
        Optional<String> opt2 = Optional.of("java");
        
        String result1 = opt1.or(()-> opt2).orElse("default");
        String result2 = opt2.filter(s -> s.length() > 10)
                           .or(()-> Optional.of("fallback"))
                           .get();
        
        System.out.println(result1);
        System.out.println(result2);
    }
}