CODEWITHSUNDEEP
javahibernate
Tejas
Tejas

Reputation: 2475

Correct way to return resultset of a query in java

I want to know what is the correct way to return resultset in form of some Collection. Or should I create class instances of same class and then return it (how to do that ?) What is the common practice to do this? Or should I learn Hibernate and implement that? 

public class Author {

private String table_name = "authors";

int id;
String full_name;
String location;
int age;
String details;


/** Getter Setter Methods  here ....*/

/** Constructor here.... */


/* Returns all Authors */
public ArrayList all() {

    ArrayList<HashMap<String, String>> list = new ArrayList<HashMap<String, String>>();

    /* TODO : figure out which collection is suitable .*/
    DbHelper dbHelper = new DbHelper();
    Connection conn = dbHelper.getConnection();
    ResultSet rs = null;
    Statement stmt = null;
    try {

        stmt = conn.createStatement();
        String query = "SELECT * FROM authors";
        rs = stmt.executeQuery(query);

        while (rs.next()) {
            HashMap<String, String> hashmap = new HashMap<>();
            int id = rs.getInt(1);
            hashmap.put("id",rs.getString(1));
            hashmap.put("full_name", rs.getString(2));
            hashmap.put("location", rs.getString(3));
            hashmap.put("age", rs.getString(4));
            hashmap.put("details", rs.getString(5));
            list.add(id,hashmap);

           //hashmap.clear();

        }

    } catch (SQLException ex) {
        Logger.getLogger(Author.class.getName()).log(Level.SEVERE, null, ex);
        System.out.println("you are fuckt");
    } finally {
        try {
            rs.close();
            stmt.close();
            conn.close();
        } catch (SQLException ex) {
            Logger.getLogger(Author.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
    return list;
}

}

Upvotes: 2

Views: 659

Answers (2)

rishi
rishi

Reputation: 1842

I would say you should go for hibernate. you will get the list of objects just by performing "list()" method.

code for your reference

List<Authors> al =   this.sessionFactory.getCurrentSession().createQuery("from    Authors").list();

Hibernare provides many other advantages too. Its definitely better option than JDBC.

JDBC alternative:

best practices says that u should return a DTO(Data transfer object) from DAO layer because it is advisable to get the relevant data in one go from DB so u can minimize the DB hits. Follow This:

           List<YourDTO> al  = new ArrayList<yourDTO>();

YourDTO is:

 class YourDTO
 {
      private int id:
      private Authors authors;

      // getters and setters
 }

read the data from resultSet as your doing then create the objects of Authors , set the fields , add them to ArrayList with id.

Upvotes: 2

Vlad Mihalcea
Vlad Mihalcea

Reputation: 153700

There are many good options available:

  1. Spring JDBC is a very good choice for mostly read db apps.
  2. Jooq is a one of the most advanced java querying alternatives, but it's free of charge only for open-source dbs.
  3. MyBatis and QueryDSL have great sql querying features, but don't match Hibernate in the create/update/delete part.
  4. Hibernate is great for domain driven models, especially for managing complex state changes, polymorphic types. It has great features like optimistic locking, dirty checks, transactional unit of works, first and second level caches, but it takes some time to master it having a steep learning curve.

Try Spring JDBC first and if that's not enough than invest your time and effort into Hibernate.

Upvotes: 1

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