Optional<T> in jdk8 will help with null:
http://download.java.net/jdk8/docs/api/java/util/Optional.ht...
http://download.java.net/jdk8/docs/api/java/util/Optional.ht...
optionalF.map( _.whatever ).getOrElse(fallback)
(optionalF <+> optionalFallback).getOrElse(finalFallback)
optional match {
case Some(x) => whatever(x)
case None => fallback
}
The speed benefit is well known, as is the corollary, premature optimisation. I expect checking for null is even faster if speed is the main concern. It's an engineering tradeoff, just like making the abstraction to a monad (or monad plus). In the normal course of events I'm more concerned about flexibility than performance and would prefer the abstraction.
resultOption match {
case Some(x) => println(x)
case None => println("error")
}
if (resultOption.isDefined) {
println(resultOption.get)
} else {
println("Error")
}
import java.util.Optional;
public class Scratch {
public static void main(String... args) {
Optional<String> foo = Optional.of("foo");
Optional<String> bar = Optional.empty();
System.out.println(foo.orElse("Error"));
System.out.println(bar.orElse("Error"));
foo.map(Print::print).orElseGet(() -> Print.print("Error"));
bar.map(Print::print).orElseGet(() -> Print.print("Error"));
foo.ifPresent(Print::print);
}
static class Print {
public static <T> T print(T val) {
System.out.println(val);
return val;
}
}
}