因为它几乎与可选不匹配，也许您可​​能会重新考虑逻辑：

As it almost but not really matches Optional, maybe you might reconsider the logic:

Java 8的表现力有限：

Java 8 has a limited expressiveness:

Optional<Elem> element = ...
element.ifPresent(el -> System.out.println("Present " + el);
System.out.println(element.orElse(DEFAULT_ELEM));

此处地图可能会限制元素上的视图：

Here the map might restrict the view on the element:

element.map(el -> el.mySpecialView()).ifPresent(System.out::println);

Java 9：

element.ifPresentOrElse(el -> System.out.println("Present " + el,
                        () -> System.out.println("Not present"));

一般来说，两个分支是不对称的。

In general the two branches are asymmetric.