To Optional or not to Optional

I recently had an interesting conversation with my colleagues about the usage of Optional's in Java. It all revolves around this article.

So, I quickly sketched the following code to highlight the idea:

import java.util.Optional;

public class OptionalEvaluationTest {
 public static void main(String[] args) {
  test1(); // non lazy execution of orElse().
  test2();
  test3();
  test4();
 }

 private static void test1() {
  System.out.println("Test 1");
  Optional<Integer> oi = Optional.ofNullable(3);
  oi.map(OptionalEvaluationTest::intToString)
   .orElse(defaultString());
  System.out.println("----");
 }

 private static void test2() {
  System.out.println("Test 2");
  Optional<Integer> oi = Optional.ofNullable(null);
  oi.map(OptionalEvaluationTest::intToString)
   .orElse(defaultString());
  System.out.println("----");
 }

 private static void test3() {
  System.out.println("Test 3");
  Optional<Integer> oi = Optional.ofNullable(3);
  oi.map(OptionalEvaluationTest::intToString)
   .orElseGet(OptionalEvaluationTest::defaultString);
  System.out.println("----");
 }

 private static void test4() {
  System.out.println("Test 4");
  Optional<Integer> oi = Optional.ofNullable(null);
  oi.map(OptionalEvaluationTest::intToString)
   .orElseGet(OptionalEvaluationTest::defaultString);
  System.out.println("----");
 }

 private static String intToString(int i) {
  System.out.println("converter called!");
  return Integer.toString(i);
 }

 private static String defaultString() {
  System.out.println("default called!");
  return "default";
 }
}

which yields the following result:

---

Test 1
converter called!
default called!
----
Test 2
default called!
----
Test 3
converter called!
----
Test 4
default called!
----

---

What we see is that .orElse() is executed always, aka is not lazy executed. This may become a performance issue if used unwisely. Tend to prefer .orElseGet() instead.