13.7k
2013-11-08 15:51:34
private static final boolean enableFast = false;
// ...
if (enableFast) {
// This is removed at compile time
}
Conditionals like that shown above are evaluated at compile time. If instead you use this
private static final boolean enableFast = "true".equals(System.getProperty("fast"));
Then any conditions dependent on enableFast will be evaluated by the JIT compiler. The overhead for this is negligible.
This solution is better then mine. When I tried to initialize the variables with a presetted outer value the running time went back to 3 seconds. But when I defined the variables as static class variables (and not a function local variable) the running time returned to 1 second. Thanks for the help.
IIRC, this even worked before Java had a JIT compiler. The code was removed by
javacI think. This only worked if the expression for (say)enableFastwas a compile time constant expression.Yes, but this conditional must reside within a method, correct? What about the case where we have a bunch of private static final Strings that we'd like to set. (e.g. a set of server URLs that are set differently for production vs. staging)
@tomwhipple : true, plus this doesn't allow you to do something like :
private void foo(#ifdef DEBUG DebugClass obj #else ReleaseClass obj #endif )what about imports (for example, regarding to classpath)?