更新Airplane时出现Cannot resolve method 'equals(long)'错误求助

我正在为机场APP构建REST API，在更新与Airline存在多对一关系的Airplane时，尝试校验飞机关联的航空公司ID是否与请求传入的ID一致，但代码中的equals()方法报错，提示“Cannot resolve method 'equals(long)'”，找不到匹配的方法调用。

出错的updateAirplane方法代码 #

@Override
public AirplaneDto updateAirplane(long airlineId, long airplaneId, AirplaneDto airplaneDto) {

    Airline airline = airlineRepository.findById(airlineId).orElseThrow(
            () -> new ResourceNotFoundException("Airline", "id", airlineId));

    Airplane airplane = airplaneRepository.findById(airplaneId).orElseThrow(
            () -> new ResourceNotFoundException("Airplane", "id", id)); // 此处存在变量未定义错误：id应为airplaneId

    if(!airplane.getAirline().getId().equals(airline.getId())) {
        throw new AirportAPIException(HttpStatus.BAD_REQUEST, "Airplane does not belong to the Airline");
    }

    return null;
}

Airplane实体类 #

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor

@Entity
@Table(name = "airplane")
public class Airplane {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String aircraftRegistration;
    private String model;
    private long capacity;
    private String code;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "airline_id", nullable = false)
    private Airline airline;
}

Airline实体类 #

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor

@Entity
@Table(name = "Airline", uniqueConstraints = {@UniqueConstraint(columnNames = {"name"})})
public class Airline {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String name;
    private String headquarters;

    @OneToMany(mappedBy = "airline", cascade = CascadeType.ALL, orphanRemoval = true)
    private Set<Airplane> airplanes = new HashSet<>();
}

解决方案 #

1. 直接用==比较基本类型数值 #

实体类中的id是基本类型long，基本类型没有equals()方法，直接用==比较数值即可：

if (airplane.getAirline().getId() != airline.getId()) {
    throw new AirportAPIException(HttpStatus.BAD_REQUEST, "Airplane does not belong to the Airline");
}

2. 将ID类型改为包装类Long（推荐） #

把Airplane和Airline中的private long id;改为private Long id;，这样ID就变成对象类型，可以正常调用equals()方法。这也是JPA最佳实践之一，适配数据库主键可能为null的场景。

额外修复 #

updateAirplane方法中存在编译错误：new ResourceNotFoundException("Airplane", "id", id)里的id变量未定义，需替换为传入的airplaneId：

Airplane airplane = airplaneRepository.findById(airplaneId).orElseThrow(
        () -> new ResourceNotFoundException("Airplane", "id", airplaneId));

内容的提问来源于stack exchange，提问作者Sokoya Nifemi