Coding practice - Which coding approach should I use?

Question

Sorry for such a vague title. Did not think of good one.

Situation:

Have a List of User objects.
Need to create array for UserInfo object.
UserInfo object is created is based on information in User object. (Currently has a method for this)

Which is better in such a situation?

Should I pass whole list of User to User to UserInfo conversion method.
or Should I loop over list of User and pass each user object to conversion method and get UserInfo for it.

Examples:

List<User> users = .....;
UserInfo[] userInfos = getUserInfoFromUser(users); //(conversion method will loop and generate array, then return it.)

or

List<User> users = .....;
UserInfo[] userInfos = new UserInfo[users.size()]
for (int j = 0; j < users.size(); j++) {
    userInfos[j] = getUserInfoFromUser(users.get(j));
}

In first approach we pass a big object(list of User) as an argument and in second we call same method multiple times.Which is better?

The size of User list will be range from 25-200 objects in it.

In the first version userInfos = getUserInfosFromUsers(users) without .get(j) — Joop Eggen
– Joop Eggen, Commented Dec 20, 2011 at 9:30

Michael Borgwardt · Accepted Answer · 2011-12-20 09:31:03Z

5

How about having two conversion methods, one that takes a User and returns a UserInfo (this could and probably should be a constructor of UserInfo), and one that takes a List, does the looping and internally calls the first one?

The size of the list is not relevant.

answered Dec 20, 2011 at 9:31

Michael Borgwardt

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1 Comment

OpenSauce Over a year ago

I agree - the list method is more convenient for use right now and reduces bloat, but the single-User method is more modular and will be easier to re-use if your requirements change or are extended.

dogbane · Accepted Answer · 2011-12-20 09:33:25Z

2

I think it depends on how often you will doing this, because you don't want to repeat the same loop in multiple places in your code.

I would suggest creating two methods, one which returns the info for a single user and the other which returns info for a list of users:

public UserInfo[] getInfoForUsers(List<User> users) {
    UserInfo[] userInfos = new UserInfo[users.size()];
    for (int j = 0; j < users.size(); j++) {
        userInfos[j] = getInfoForUser(users.get(j));
    }
    return userInfos;
}

public UserInfo getInfoForUser(User u) {

}

answered Dec 20, 2011 at 9:33

dogbane

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Comments

Vaandu · Accepted Answer · 2011-12-20 09:30:29Z

0

I prefer the first approach as it is simple, also, argument will be the address of the users object. So doesn't matter big or small in that case.

answered Dec 20, 2011 at 9:30

Vaandu

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Comments

paly · Accepted Answer · 2011-12-20 09:31:28Z

0

In the both cases, Java passes reference to an object. In 1st case, it's reference to collection of Users and in 2nd to an User.

answered Dec 20, 2011 at 9:31

paly

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Comments

Deian · Accepted Answer · 2011-12-20 09:31:45Z

0

I would recommend to use the first option: pass the whole array!

Reducing the number of function calls definitely pays out.

answered Dec 20, 2011 at 9:31

Deian

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Joop Eggen · Accepted Answer · 2011-12-20 09:32:13Z

0

There is no difference: in the first version the function implementation would do the second version. Furthermore probably would like to have a function User -> UserInfo.

answered Dec 20, 2011 at 9:32

Joop Eggen

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