Читать книгу OCP Oracle Certified Professional Java SE 17 Developer Study Guide - Jeanne Boyarsky - Страница 177

While possible, it is a bad practice to reassign a pattern variable since doing so can lead to ambiguity about what is and is not in scope.

if(number instanceof Integer data) { data = 10; }

The reassignment can be prevented with a final modifier, but it is better not to reassign the variable at all.

if(number instanceof final Integer data) { data = 10; // DOES NOT COMPILE }