How to remove warnings[NOT by @SuppressWarnings ] in List and Iterator [What generic type to be applied on both line of code]

Question

I want to remove warning by mentioning generic type in List result and Iterator orderRecord

OrderStorage class

public class OrderStorage {

    private static final String GET_TOTAL_ORDERS_QUERY = "SELECT c.name as customerName ,o.orderDate,p.name as productName  "
            + "FROM Customer c LEFT JOIN Order o WITH o.customer = c LEFT JOIN Product p WITH o.product = p";

    public static List<TotalOrder> getOrder() {

        List<TotalOrder> resultList = new ArrayList<TotalOrder>();
        Session session = SessionCreator.getSession();
        session.beginTransaction();
        List result = session.createQuery(GET_TOTAL_ORDERS_QUERY).getResultList();
        Iterator orderRecord = result.iterator();
        while (orderRecord.hasNext()) { 
            TotalOrder customerOrder = new TotalOrder();
            Object values[] = (Object[]) orderRecord.next();
            customerOrder.setCustomerName(String.valueOf(values[0]));
            customerOrder.setOrderDate(String.valueOf(values[1]));
            customerOrder.setProductName(String.valueOf(values[2]));
            resultList.add(customerOrder);
        }
        session.close();
        return resultList;
    }
}

TotalOrder class

private String customerName;

private String orderDate;

private String productName;

Getters and Setters method

Warnings is :

List is a raw type. References to generic type List should be parameterized

Iterator is a raw type. References to generic type Iterator should be parameterized

score 0 · Answer 1 · answered Jun 17 '19 at 10:12

You need to create a typed query by using another overload of createQuery method.

Doc for createQuery method says:

<T> Query<T> createQuery(java.lang.String queryString,
                         java.lang.Class<T> resultType)
Create a typed Query instance for the given HQL/JPQL query string.

score 0 · Answer 2 · answered Jun 17 '19 at 10:48

You can either use Object[] or, probably better, use a ResultTransformer, that way you don't even need to use an iterator.

return session.createQuery(GET_TOTAL_ORDERS_QUERY)
         .setResultTransformer( Transformers.aliasToBean( TotalOrder.class ) )
         .getResultList();

This will let hibernate map the result directly to a TotalOrder, no need to map yourself. It might be needed to add an as orderDate to your query for the order field.

For more ways to map results check this.

How to remove warnings[NOT by @SuppressWarnings ] in List and Iterator [What generic type to be applied on both line of code]

2 Answers2