scjp - Java char to byte casting

Question

I have been testing the char casting and I went through this:

public class Test {
    public static void main(String a[]) {
        final byte b1 = 1;
        byte b2 = 1;
        char c = 2;

        c = b1; // 1- Working fine
        c = b2; // 2 -Compilation error
    }
}

Can anyone explain why it's working fine in 1 when I added a final to the byte?

Answer 1

When the variable is final, the compiler automatically inlines its value which is 1. This value is representable as a char, i.e.:

c = b1;

is equivalent to

c = 1;

In fact, according to this section on final variables, b1 is treated as a constant:

A variable of primitive type or type String, that is final and initialized with a compile-time constant expression (§15.28), is called a constant variable.