point of having an instance variable as final?

Question

what is the point of having an instance variable as final?

isn´t it better to have that variable set as a static final variable then?

cause if it can\'t be chang

Answer 1

I guess you are thinking about simple case such as:

 private final int num = 3;

That can be better written as:

 private static final int NUM = 3;

However, often you will have references to objects that are mutable, and therefore cannot be shared between classes:

 private final List children = new ArrayList();

Or perhaps, a value passed into or derived in the constructors:

 public final class MyThing {
      private final String name;
      public MyThing(String name) {
          this.name = name;
      }
      [...]
 }

Note: final fields can be assigned in constructors (or instance initialiser), not just as part of the declaration.