java - 如何获取两列的值并存入ArrayList

Question

我正在使用 Spring 框架，在下面的代码中，我想从数据库中获取经纬度并将其存储在 ArrayList 中，然后计算它们之间的距离。

问题是当我按照以下方式执行此操作时，我无法弄清楚如何获取变量中两列的值 [Ljava.lang.Object;无法转换为 java.lang.Double 抛出异常

有人能帮帮我吗？我读到我们可以使用 2D ArrayList 但我如何在以下代码中使用 ArrayList

RiderService.java

@Component
public class RiderService {

     @Autowired RiderLocationRepository riderLocationRepository;

    public float Location(Double lattitude,Double longitude)
    {
        Double lat2=24.927437;
        Double lng2=67.094412;

          ArrayList<Double> allRidersLocation  = new ArrayList<Double>();
          allRidersLocation= riderLocationRepository.findAllRidersLocation();
          Iterator<Double> iterator = allRidersLocation.iterator();
            while (iterator.hasNext()) {
                System.out.println(" DB value " +  iterator.next().doubleValue());
            } 
            float distance=distFrom(lattitude, longitude, lat2, lng2);
            System.out.println("Distance : " + (distance/1000));
            return distance;
    }

RiderRepository

public interface RiderLocationRepository extends JpaRepository<RiderLocation, Long>{

    @Query("select r.latitude,r.longitude from RiderLocation r ")
    ArrayList<Double>  findAllRidersLocation();

}

Answer 1

试试这个，

public float Location(Double lattitude,Double longitude)
    {
        Double lat2=24.927437;
        Double lng2=67.094412;

          List<RiderLocation> allRidersLocation  = riderLocationRepository.findAll();
          for (RiderLocation riderLocation : allRidersLocation) {
            float distance=distFrom(riderLocation.getLattitude(), riderLocation.getLongitude(), lat2, lng2);
            System.out.println("Distance : " + (distance/1000));
            return distance;
    }
    }

默认情况下，findAll() 方法在 CrudRepository 上可用

public interface RiderLocationRepository extends JpaRepository<RiderLocation, Long>{

}