Casting reference variable without the double parentheses

Question

Given the below two classes :

class A {}

class B extends A {
    int b;
}

Based on the following operators precedence table : http://www.cs.bilkent.edu.tr/~guvenir/courses/CS101/op_precedence.html.

Both operators () and . have the same priority and they evaluated from left to right (associativity).

A a = new B();
assert (B)a.b == 0;

the above code snippet should compile and asserts successfully as the parentheses operator is evaluated first (casting reference a to type B) then accessing the casted reference's b member variable which returns a value of 0.

Why is the above statement isn't the case ?

Answer 1

You are confusing the () Parentheses in precedence 15 with the ( type ) Unary type cast in precedence 13.

The . Member selection in precedence 15 is higher than the type cast, so (B)a.b means (B) (a.b), which is why you need to write ((B) a).b to get what you want.