Are there any ways to map the result set at sql2o as generics?

Question

I'm writing database client using sql2o library. There are a lot of data access objects in my project, so I supposed to have lot of similar functions for getting access to the tables. For example, for class Persons.

public List<Persons> getPersonsData(){
   String sql = "SELECT * FROM " + PERSONS;
   try(org.sql2o.Connection con = sql2o.open()) {
      return con.createQuery(sql).executeAndFetch(Persons.class);
   }
}

Are there any ways to optimize it? I was thinking about using generics, but as I know there no ways to get instance of generic class. Is it really impossible to create something like this?

public class Getter<T> {
    public List<T> getGenericClass(){
        String sql = "SELECT * FROM " + T.tableName;
        try(org.sql2o.Connection con = sql2o.open()) {
            return con.createQuery(sql).executeAndFetch(T.class);
        }
    }
}

Answer 1

We managed that creating a Store class

 public class Store<T> {
    private T value;

    public void set(T object){
        value = object;
    }

    public T get(){
        return value;
   }
}

and modify your GenericClass

public class GenericClass{
     public <T> void storeGenericClass(Store<T> store, Class<T> clazz){
            String sql = "SELECT field1, field2 FROM MYTABLE WHERE ID = 1";
            try(org.sql2o.Connection con = sql2o.open()) {
                store.set(con.createQuery(sql).executeAndFetchFirst(clazz));
            }
        }

      public <T> void storeGenericClass(List<T> store, Class<T> clazz){
            String sql = "SELECT field1, field2 FROM " + 
              clazz.getName().toUpperCase();
            try(org.sql2o.Connection con = sql2o.open()) {
                store.addAll(con.createQuery(sql).executeAndFetch(clazz));
            }
        }

}

Use the same className as tableName is not a best practice. But if you map each class with a table, you can do in this way

  public class GenericClass{
    ...
     public <T> void storeGenericClass(List<T> store, Class<T> clazz){
            String sql = "SELECT field1, field2 FROM " + 
           clazz.getName().toUpperCase();
            try(org.sql2o.Connection con = sql2o.open()) {
                store.addAll(con.createQuery(sql).executeAndFetch(clazz));
            }
        }
     ...
}

To instantiate:

public class MyClass {

    public String field1, field2;
}


...
    GenericClass generic= new GenericClass(sql2o);
    Store<MyClass> store = new Store<>();
    generic.storeGenericClass(store, MyClass.class);
    MyClass retrieved = store.get();
    System.out.println("My Class fields are: "+retrieved.field1 + "-"+retrieved.field2);
...