CODEWITHSUNDEEP
java
wishman
wishman

Reputation: 774

What kind of Java List should I use to maintain a set of data

I have a dataset, and I'm not sure which type of List or Map to use in Java. Following is a sample dataset. There are 2 columns, Users and Errors.

A user can be repeated. Errors are random and there won't be any duplicates.

Users Errors

User A Error 1

User B Error 2

User A Error 3

User C Error 4

and I should be able to use the list to get all errors per user at the end.

I tried a hashmap, but it only retrieves the last entry for user.

Thanks in advance.

Upvotes: 1

Views: 36

Answers (2)

Krzysztof Krasoń
Krzysztof Krasoń

Reputation: 27496

You can use Map of String to List. Depending on java version you might need to do manual checks if given key exists (in such case add the error) or doesn't (create list and add a single error)

Upvotes: 0

Eran
Eran

Reputation: 393956

You can use a HashMap<User,List<Error> (not sure if there are User and Error classes or if they are represented by Strings or some numeric type, but you get the idea).

This will make it easy to obtain the List of all errors for a given user.

Upvotes: 4

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