Java OCA OCP Practice Question 2184

Question

Which of the following can fill in the blank to print out the numbers 161, 183, and 201 in any order? 

class Car { /*from  w  w  w .  j a  v  a 2 s .  co  m*/
   private int speed; 
   public Car(int n) { 
      speed = n; 
   } 
   public int getSpeed() { 
      return speed; 
   } 
} 
public class Main { 
   public static void main(String[] args) { 
      Stream<Car> runners = Stream.of(new Car(183), 
         new Car(161), new Car(201)); 
      OptionalInt opt = runners.                              ; 
   } 
} 

A.  map(Car::getSpeed).peek(System.out::println).max()
B.  mapToInt(Car::getSpeed).peek(System.out::println).max()
C.  peek(System.out::println).mapToInt(Car::getSpeed).max()
D.  peek(System.out::println).mapToInt(Car::getSpeed).max()
E.  None of the above



B.

Note

Options C and D are incorrect because they print the Car object rather than the int value it contains since peek() is called before mapping the value.

The Car object is something like Car@7d12e123.

Option A is incorrect because the map() method returns a Stream<Integer>.

While Stream<Integer> does have a max() method, it requires a Comparator.

By contrast, Option B uses mapToInt(), which returns an IntStream and does have a max() method that does not take any parameters.

Option B is the only one that compiles and outputs the int values.




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