Why instance variable to be final?

Question

I read this question about immutable objects and was left with a question regarding immutable objects and final field:

Why do we need instance variable in immutab

Answer 1

In immutable class you can not change the state of it's property/field. Generally it is done by not providing setter method to the client code of the class.

And the combination of static final keyword is used to make a variable constant. A variable declared final can never be change it's value once it has been initialized.

Since in immutable class you never need to change the property/field state, so it is better to make it final.