Why is an if/else if/else for a simple boolean not giving an "unreachable code" error
JavaBooleanUnreachable CodeJava Problem Overview
Why is this code not giving an "unreachable code" error? Since a boolean can only be true or false.
public static void main(String args[]) {
boolean a = false;
if (a == true) {
} else if (a == false) {
} else {
int c = 0;
c = c + 1;
}
}
Java Solutions
Solution 1 - Java
From JLS 14.21. Unreachable Statements
> It is a compile-time error if a statement cannot be executed because it is unreachable.
and
> The else-statement is reachable iff the if-then-else statement is reachable.
Your if-then-else statement is reachable. So, by the definition the compiler thinks that the else-statement is reachable.
Note: Interestingly the following code also compiles
// This is ok
if (false) { /* do something */ }
This is not true for while
// This will not compile
while (false) { /* do something */ }
because the reachability definition for while is different (emphasis mine):
> The contained statement is reachable iff the while statement is reachable and the condition expression is not a constant expression whose value is false.