1z0-809

Review 248 1Z0-809 practice questions with answer explanations and community insights.

Question 1

Given the definition of the Vehicle class: Class Vehicle { int distance; Vehicle (int x) { this distance = x; } public void increSpeed(int time) { int timeTravel = time; //line n1 //line n3 class Car { int value = 0; public void speed () { value = distance /timeTravel; //line n2 System.out.println ("Velocity with new speed"+value+"kmph"); } } speed(); //line n3 } } and this code fragment: Vehicle v = new Vehicle (100); v.increSpeed(60); What is the result?

  1. Velocity with new speed 1 kmph
  2. A compilation error occurs at line n1.
  3. A compilation error occurs at line n2.
  4. A compilation error occurs at line n3.

Question 2

Given: IntStream stream = IntStream.of (1,2,3); IntFunction inFu= x -> y -> x*y; //line n1 IntStream newStream = stream.map(inFu.apply(10)); //line n2 newStream.forEach(System.output::print); Which modification enables the code fragment to compile?

  1. Replace line n1 with: IntFunction<UnaryOperator> inFu = x -> y -> x*y;
  2. Replace line n1 with: IntFunction<IntUnaryOperator> inFu = x -> y -> x*y;
  3. Replace line n1 with: BiFunction<IntUnaryOperator> inFu = x -> y -> x*y;
  4. Replace line n2 with: IntStream newStream = stream.map(inFu.applyAsInt (10));

Question 3

Given the code fragment: List values = Arrays.asList (1, 2, 3); values.stream () .map(n -> n*2) //line n1 .peek(System.out::print) //line n2 .count(); What is the result?

  1. 246
  2. The code produces no output.
  3. A compilation error occurs at line n1.
  4. A compilation error occurs at line n2.

Question 4

Given the code fragment: public class Foo { public static void main (String [ ] args) { Map unsortMap = new HashMap ( ); unsortMap.put (10, "z"); unsortMap.put (5, "b"); unsortMap.put (1, "d"); unsortMap.put (7, "e"); unsortMap.put (50, "j"); Map treeMap = new TreeMap (new Comparator ( ) { @Override public int compare (Integer o1, Integer o2) {return o2.compareTo (o1); } } ); treeMap.putAll (unsortMap); for (Map.Entry entry : treeMap.entrySet () ) { System.out.print (entry.getValue () + " "); } } } What is the result?

  1. A compilation error occurs.
  2. d b e z j
  3. j z e b d
  4. z b d e j

Question 5

Which two reasons should you use interfaces instead of abstract classes? (Choose two.)

  1. You expect that classes that implement your interfaces have many common methods or fields, or require access modifiers other than public.
  2. You expect that unrelated classes would implement your interfaces.
  3. You want to share code among several closely related classes.
  4. You want to declare non-static on non-final fields.
  5. You want to take advantage of multiple inheritance of type.