Boolean expressions optimizations in Java

Question

Consider the following method in Java:

public static boolean expensiveComputation() {
    for (int i = 0; i < Integer.MAX_VALUE; ++i);
    return false;
}         


        

Answer 1

Because expensiveComputation() may have side-effects.

Since Java doesn't aim to be a functionally pure language, it doesn't inhibit programmers from writing methods that have side-effects. Thus there probably isn't a lot of value in the compiler analyzing for functional purity. And then, optimizations like you posit are unlikely to be very valuable in practice, as expensiveComputation() would usually be required to executed anyway, to get the side effects.

Of course, for a programmer, it's easy to put the b first if they expect it to be false and explicitly want to avoid the expensive computation.