optional.map(x -> true).orElse(false) → optional.isPresent()optional.map(x -> Optional.of(x.trim())).orElseGet(Optional::empty) → optional.map(String::trim)optional.map(x -> (String)x).orElse(null) → (String) optional.orElse(null)Optional.ofNullable(optional.orElse(null)) → optionalval = optional.orElse(null); val != null ? val : defaultExpr → optional.orElse(defaultExpr)val = optional.orElse(null); if(val != null) expr(val) → optional.ifPresent(val -> expr(val))2017.2 の新機能です