CODEWITHSUNDEEP
javainheritancecollections
jktravis
jktravis

Reputation: 1568

Create Custom Collection in Java

I'm not quite sure how to do this, but I find myself using a list of lists quite often in this particular project. I think I'd like to refactor this into it's own collection. Basically, it's a list of users and their attributes. The object I'm using is a List<List<String>>. I think I'd like to make a drop-in replacement that maybe extends ArrayList and call it UserList or something similar.

Note: my only real goal is to keep from typing List<List<String>> everywhere.

What would be the best approach to take with this?

EDIT: Thanks. I guess I knew something could be better. Just couldn't quite put my finger on it. I had initially avoided creating a User class because I wasn't sure how I would easily be able to iterate over the attributes.

Upvotes: 0

Views: 3994

Answers (2)

The Guy with The Hat
The Guy with The Hat

Reputation: 11132

You shouldn't.

You'll spend a lot more time writing this new class than just typing a few extra characters.

If you really want to make a new class.

Why not like this?

public class User {

    private String attribute1;
    private String attribute2;
    //etc.

    public String getAttribute1() {
        return attribute1;
    }

    public void setAttribute1(String value) {
        attribute1 = value;
    }

    public String getAttribute2() {
        return attribute2;
    }

    public void setAttribute2(String value) {
        attribute2 = value;
    }

    //etc.
}

If you insist on using nested Lists.

I suggest creating a wrapper class that would look something like this:

public class Users {

    private List<List<String>> twoDList;

    public String get(int x, int y) {
        return twoDList.get(y).get(x);
    }

    public void set(int x, int y, String value) {
        twoDList.set(y, twoDList.get(y).set(x, value));
    }

    //etc.
}

Upvotes: 3

rgettman
rgettman

Reputation: 178363

There is no need to create a custom List<List<String>> for these requirements.

Create a User class to store all the attributes, then create a List<User>.

Upvotes: 5

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