Exam 1z0-819 topic 1 question 121 discussion

answer: B A. Failed there is no such method as average() in Stream B. correct IntStream OptionalDouble average() public double orElse​(double other) If a value is present, returns the value, otherwise returns other. so it returns double C. Failed Failed this expression returns OptionalDouble so double average = players.stream().mapToDouble(a -> a.score).average(); returns MyClass.java:17: error: incompatible types: OptionalDouble cannot be converted to double D. Failed there is no such method as average() in Stream

B => to contact orElse return a double. Lonely average return a optionalDouble OTHHERS stream not contain average, InsStream or InDouble yes but with orElse clause return a primitive value

tested.

The correct statement to insert on line 1 to calculate the average of the Player's score is option B: `players.stream().mapToInt(a -> a.score).average().orElse(0.0);`. This statement uses the `mapToInt` method to convert the stream of `Player` objects into an `IntStream` of their scores, then calculates the average using the `average` method, and finally returns the result or 0.0 if no result is present using the `orElse` method.

double average = players.stream().mapToInt(a -> a.score).average().orElse(0.0);