Why final instance class variable in Java?

Question

If instance variable is set final its value can not be changed like

public class Final {

    private final int b;

    Final(int b) {
        this.b = b; 
         


        

Answer 1

In "C/C++" terms:

Thing * a;
Thing * const b;
Thing const * c;
Thing const * const d;

The "final" in Java is closest to "b". "b" is a constant pointer to a Thing. "b" cannot be changed to point to a different Thing, but the Thing itself may be changed.

Java doesn't have a representation for "c" and "d". "c" is a pointer to a constant Thing. "c" may point to other Things, but the Things it points to cannot be changed (at least, not through "c" itself)

"d" combines "b" and "c": "d" is a constant pointer to a constant Thing.

Oh, and "a" of course is just nothing special.

Hm...In Java, not everything is an object so the rules are a little different.

final int f = 9;

Which, in C is much like

int const f = 9;

Which means you cannot change "f" or its integer value.

NOTE:

int const f;
const int g;

both mean the same thing, but "f" IMHO has clearer meaning. "g" is unfortunately very common.