How do i make a constant-like instance of class in Java?

Question

I am trying to write a simple game, and in that game, there is a class called Fighter, and instances of that class can attack other instances.

I want to make an instance of that class that is always defined and has special properties(i know how to do that please don't try to answer that) so that it can be used as a power player of some sort.

I agree with the person above that it is very unclear what you are trying to say. Do you mean you want a base class that all player objects should inherit? — Steven, Dec 06 '18 at 16:53
Do you need a parent class where common code is created for all children, or do you need a class that cannot be changed (constant-like). For the latter you need to add "final" to your class. public final class AdminFighter — fpezzini, Dec 06 '18 at 16:56
This is not a code writing service, improve your question with what you have done so far and an explanation of how the code needs to be improved or what issue you have with it. — Joakim Danielson, Dec 06 '18 at 17:17

score 1 · Accepted Answer · answered Dec 06 '18 at 17:17

1

What you probably want is:

public class Fighter {
    public static final Fighter ADMIN_FIGHTER = new Fighter(whatever-args ...);

answered Dec 06 '18 at 17:17

rghome

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It works but every time i try to execute a method it returns a null pointer exeption. – DexterHaxxor Dec 06 '18 at 18:57
Well that's just a bug in your program. For help see https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it. – rghome Dec 06 '18 at 19:43

score 0 · Answer 2 · answered Dec 06 '18 at 17:25

you can use Singleton pattern like this

public final class AdminFighter {
   private static final AdminFighter instance = new AdminFighter();
   private AdminFighter(){}
   public static AdminFighter instance() {
       return instance;
   }
}

so whereever you are in the project you can use like this

AdminFighter constant = AdminFighter.instance();

and this always return the same instance of AdminFighter like a constant.

NOTE: avoid global constants like this example, they will turn in future headaches and they are sign of poor design. There are tons of blog post discussing about this.

How do i make a constant-like instance of class in Java?

2 Answers2