Question

I’m trying to sync to user list by building a map that contains a username as a key and an user object as the value. Once the map has been built, I’m having difficulties retrieving the object values. Below is the code I’m using.

private Map<String, User> map = new HashMap<String, User>();

I’m populating the map key and object as followed.

        List<User> users = session.createCriteria(User.class).list();

        for(ApplicationUser user : users) {
            map.put(user.getUserName(), user);
        }

I’m trying to retrieve the data as followed,

        List<Person> persons = session.createCriteria(Person.class).list();
        for (Person p : persons) {
            User user = map.containsKey(p.getUsername()) ? map.get(p.getUsername()) : new User();
            //Email is always null. 
            System.out.println(user.getEmail());
        }

Could someone help point me in the right direction on how to retrieve the object values from my map. Thanks

Answer 1

First, you should change your loop to this:

   for (Person p : persons) {
        String username = p.getUsername();
        User user = map.get(username);
        if (user != null) {
           System.out.println(user.getEmail());
        } else {
          System.out.println("User " + username + " is unknown");
        }
    }

Then set a breakpoint in the loop and debug your code. It looks correct so far. Maybe you are just not setting email in User or the users from persons are not in your map.