RFR 8071670: java.util.Optional: please add a way to specify if-else behavior

[Daniel Fuchs]

Hi Paul,

This looks good - I have noticed one copy/paste error in the javadoc
though:

OptionalInt.java:

looks like the throws clause of ifPresent and ifPresentOrElse have been
interverted:

  138      * @throws NullPointerException if a value is present and 
{@code action} is
  139      * null, or a value is not present and {@code emptyAction} is 
null.
  140      */
  141     public void ifPresent(IntConsumer action) {
  142         if (isPresent) {
  143             action.accept(value);
  144         }
  145     }
  146
  147     /**
  148      * If a value is present, perform the given action with the value,
  149      * otherwise perform the given empty-based action.
  150      *
  151      * @param action the action to be performed if a value is present
  152      * @param emptyAction the empty-based action to be performed 
if a value is
  153      * not present
  154      * @throws NullPointerException if value is present and {@code 
action} is
  155      * null
  156      * @since 1.9
  157      */
  158     public void ifPresentOrElse(IntConsumer action, Runnable 
emptyAction) {


Concerning the test, should there be a test that verifies that NPE
is thrown when null is passed - as specified in the javadoc?

Best regards,

-- daniel

On 03/02/15 16:38, Paul Sandoz wrote:
> Hi,
>
> http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8071670-Optional-ifPresentOrElse/webrev/
>
> Here is another tweak to Optional (and primitives) that has some weight:
>
> /**
>   * If a value is present, perform the given action with the value,
>   * otherwise perform the given empty-based action.
>   *
>   * @param action the action to be performed if a value is present
>   * @param emptyAction the empty-based action to be performed if a value is
>   * not present
>   * @throws NullPointerException if a value is present and {@code action} is
>   * null, or a value is not present and {@code emptyAction} is null.
>   * @since 1.9
>   */
> public void ifPresentOrElse(Consumer<? super T> action, Runnable emptyAction) {
>      if (value != null) {
>          action.accept(value);
>      } else {
>          emptyAction.run();
>      }
> }
>
> (In hindsight we should have been consistent and thrown NPEs regardless of the optional state. The exception throwing behaviour is consistent with ifPresent.)
>
> Previously it was kind of awkward if one had two lambdas or method refs handy, one had to do:
>
>    o.ifPresent(v -> ...);
>    if (!o.ifPresent()) {
>      ...
>    }
>
> Or just:
>
>    if (o.ifPresent()) {
>      ...
>    } else {
>       ...
>    }
>
>
> I also updated the language of the ifPresent methods to be more consistent with Collection/Stream.forEach.
>
> Paul.
>