[FIXED] Advice for code simplification for joint table

Issue

I need advice for my code simplification. I am using Struts 2, Spring, and Hibernate as framework.

File DAO:

public List<Model> getData() throws HibernateException {

    List<Model> list = new ArrayList<Model>();
    List<Object[]> res = new ArrayList<Object[]>();
    String query = "SELECT table1.*, table2.* FROM table1, table2 WHERE table1.bridge_id = table2.bridge_id";
    res = this.sessionFactory.getCurrentSession()
            .createSQLQuery(query)
            .list();

    for (Object[] row : res) {
        Model model = new Model();
        model.setName((String) row[1]);
        model.setDate((Date) row[2]);

        list.add(model);
    }
    return list;
}

I try using

while(res.next()){ ... }

but next() is not function in my project, like I am using size() to count size of the list rather than length of array.

for some reason I dont like to define function value in loop using row[0], what I want is to define the value as row["name"].

Solution

There was posible two ways to map column names to use with row data Object[] which contains only values.

1. Map column names to indeces.

    Map<String, int> map = new HashMap<>()
    map.put("name", 0); 
    map.put("date", 1);
    for (Object[] row : res) {
        Model model = new Model();
        model.setName((String) row[map.get("name")]);
        model.setDate((Date) row[map.get("date")]);
        list.add(model);
     }

2. Map Object[] to Map<String, Object> and use previous mapping

    Map<String, int> map = new HashMap<>()
    map.put("name", 0); 
    map.put("date", 1);
    
    for (Object[] row : res) {
        Model model = new Model();
        Map<String, Object> map2 = new HashMap<>();
        map2.put("name", row[map.get("name")]);
        map2.put("date", row[map.get("date")]
        model.setName((String) map2.get("name"));
        model.setDate((Date) map2.get("date"));
        list.add(model);
     }

You can create an adapter class for row which contains both mapping. The adapter takes Object[] as a constructor parameter. Then use a function getValue(String) which returns an Object from the second map.

Answered By - Roman C
Answer Checked By - Robin (JavaFixing Admin)