Let ArrayList point to another arraylist but with a filter.

[gonzalioz]

Hi all,

I have a ArrayList called messages in a class called Database.

ArrayList<Message> messages = new ArrayList<Message>();

In this arraylist are all the records of the database table called messages...


I also have a User object. In this user object I also have a list with messages. But I want to point this list to the big one but only the messages that belong to this user. However when I would add something to this list: for example: UserA.getMessages().Add(something) I want it to be added to the big one. But when I am looping through it. For example: for (Message m : UserA.getMessages()) I want it to look in the big one, but only find messages that belong to this user.

I know, it's pretty confusing. I hope you guys understand and can help me. Basically what I am looking for is some kind of filter that I can put over the user copy of the big list that will only show the messages that belong to that user but when I add something, it will be added to the big list.

Thanks in advance for your help!

[doWhile]

If I understand what you want correctly, it seems a Map might work well for you - keyed with the User and valued with the list of messages associated with that user:
The Map Interface (The Java™ Tutorials > Collections > Interfaces)