The reason for this is the use of Optional<T> in the return. Optional is not allowed to contain null. Essentially, it offers no way of distinguishing situations “it’s not there” and “it’s there, but it is set to null“. That’s why the documentation explicitly prohibits the situation when null is selected in findFirst(): Throws: NullPointerException … Read more
Yes, just format your strings in the standard String.format() way. See the method Context.getString(int, Object…) and the Android or Java Formatter documentation. In your case, the string definition would be: <string name=”timeFormat”>%1$d minutes ago</string>
Your question is based on assumption that the code which may throw NullPointerException is worse than the code which may not. This assumption is wrong. If you expect that your foobar is never null due to the program logic, it’s much better to use Optional.of(foobar) as you will see a NullPointerException which will indicate that … Read more
When n3406 (revision #2 of the proposal) was discussed, some committee members were uncomfortable with optional references. In n3527 (revision #3), the authors decided to make optional references an auxiliary proposal, to increase the chances of getting optional values approved and put into what became C++14. While optional didn’t quite make it into C++14 for … Read more
@matt has the details, but there is a (somewhat horrible, somewhat awesome) workaround. (See edit below, though) let window = app.delegate?.window??.`self`() I will leave the understanding of this line of code as an exercise for the reader. OK, I lie, let’s break it down. app.delegate?.window OK, so far so good. At this point we have … Read more
There are many similarities and just a handful of differences. (Regular) Optionals Declaration: var opt: Type? Unsafely unwrapping: let x = opt!.property // error if opt is nil Safely testing existence : if opt != nil { … someFunc(opt!) … } // no error Safely unwrapping via binding: if let x = opt { … … Read more