列出到Hashmap以创建API

Question

I have some method that return an object and a count, due to the following SQL request

public List<Sales> mostLoyal() {
    String queryString = "SELECT s, COUNT(s.saleId) as TotalNum FROM Sales s GROUP BY s.custId.custLastName ORDER BY TotalNum DESC";
    List<Sales> breakdown = em.createQuery(queryString).setMaxResults(10).getResultList();
    return breakdown;
}

I'm trying to transform this List into a Hashmap containing the object (s in the request) and the count. I've tried a lot of things but I can't figure for the life of me out how to do that.
The goal is to return this Hashmap into a json.

Answer 1

You can simply iterate through your list and place values in HashMap and return it. Should be simple.

public Map<String,Integer> mostLoyal() {
    Map<String,Integer> m = new HashMap<String,Integer>();
    String queryString = "SELECT s, COUNT(s.saleId) as TotalNum FROM Sales s GROUP BY s.custId.custLastName ORDER BY TotalNum DESC";
    List<Sales> breakdown = em.createQuery(queryString).setMaxResults(10).getResultList();

    for(Sales sale: breakdown){
      m.put(sale.getS(),sale.getCount());

    }
    return m;
}