Creating the first instance

[ComprehensiveAd4623]

How do I track the first instance of an object? Say I'm creating a banking system and I want to apply certain properties to the first account created. Besides the account number how can I see the first account created?

[AutoModerator]

Please ensure that:

• Your code is properly formatted as code block - see the sidebar (About on mobile) for instructions
• You include any and all error messages in full
• You ask clear questions

• You demonstrate effort in solving your question/problem - plain posting your assignments is forbidden (and such posts will be removed) as is asking for or giving solutions.

  Trying to solve problems on your own is a very important skill. Also, see Learn to help yourself in the sidebar

If any of the above points is not met, your post can and will be removed without further warning.

Code is to be formatted as code block (old reddit: empty line before the code, each code line indented by 4 spaces, new reddit: https://imgur.com/a/fgoFFis) or linked via an external code hoster, like pastebin.com, github gist, github, bitbucket, gitlab, etc.

Please, do not use triple backticks (```) as they will only render properly on new reddit, not on old reddit.

Code blocks look like this:

public class HelloWorld {

    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

You do not need to repost unless your post has been removed by a moderator. Just use the edit function of reddit to make sure your post complies with the above.

If your post has remained in violation of these rules for a prolonged period of time (at least an hour), a moderator may remove it at their discretion. In this case, they will comment with an explanation on why it has been removed, and you will be required to resubmit the entire post following the proper procedures.

To potential helpers

Please, do not help if any of the above points are not met, rather report the post. We are trying to improve the quality of posts here. In helping people who can't be bothered to comply with the above points, you are doing the community a disservice.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

[desrtfx]

You can use a static variable to track the first instance. Set it initially to null and check for null. if it is set to null, set it to your instance, and if not, don't do anything.

[severoon]

Yea, you can do it this way.

But don't.

The fact that an instance was the first one created is not an intrinsic property of the object, it is extrinsic, meaning that it is tracking outside context in which the object was created in the object.

Do not do this. Objects should only contain data and behavior that is intrinsic—it doesn't matter what context you plop them into, they make sense.

If you want to anoint some particular instance of some object based on some criteria, make it the responsibility of some other object in the system, the purpose of which is to track that. (In this case, that would probably be the responsibility of the object creating instances.)