Question

I am trying to get a list of objects from the Database based on a target object through reflection.
I don’t have much experience with reflection so this doesn’t work.
Is it even possible to achieve my goal?

public static List<Object> getObjectsFromDataBase(Object targetObj) {
....................
ResultSet rs = stat.executeQuery(queryToExecute);
while (rs.next()) {
     Object obj = new Object();
     for (Field property : targetObj.getClass().getFields()) {
      property.set(obj, rs.getString(property.getName()));
     }
     objListToReturn.add(obj);
}
.....................
return objListToReturn;
}

Answer 1

If the fields in the target object’s class are not public they won’t show up in getFields(). Try this:

import java.lang.reflect.Field;

public class Test
{
    public static class A
    {
        public String field1;
        public String field2;
    }
    public static void main(String[] args) throws Exception
    {
        A a = new A();
        Object b = a;
        for (Field f : b.getClass().getFields())
        {
            System.out.println(f.getName());
        }

    }
}

If you remove public, getFields() returns an empty array.