CoreTest.java

package foo.bar;

import io.atlassian.fugue.Option;
import org.junit.Test;

import java.util.Objects;
import java.util.Optional;

// https://developer.atlassian.com/blog/2015/08/optional-broken/
public class CoreTest {

  @Test
  public void optionTest() {

    Optional.<String>empty()
        .map(this::notNullString)
        .ifPresent(x -> System.out.println("empty map: " + x));
    Option.<String>none()
        .map(this::notNullString)
        .forEach(x -> System.out.println("none map: " + x));

    Optional.<String>empty()
        .flatMap(this::notEmptyString)
        .ifPresent(x -> System.out.println("empty flatmap: " + x));
    Option.<String>none()
        .flatMap(this::someString)
        .forEach(x -> System.out.println("none flatmap: " + x));

    Optional.of("x").map(this::makeNull)
        .map(this::notNullString)
        .ifPresent(x -> System.out.println("mapping null, optional: " + x));
    Option.some("x").map(this::makeNull)
        .map(this::notNullString)
        .forEach(x -> System.out.println("mapping null, option: " + x));

  }

  public String makeNull(String x) {
    return null;
  }

  public String notNullString(String x) {
    return Objects.toString(x, "got null");
  }

  public Optional<String> notEmptyString(String x) {
    return Optional.of(notNullString(x));
  }

  public Option<String> someString(String x) {
    return Option.some(notNullString(x));
  }

}