Oracle Oracle Database 1Z0-809 Questions & Answers

• Question 201:

  Given:

  class Sum extends RecursiveAction { //line n1

  static final int THRESHOLD_SIZE = 3;

  int stIndex, lstIndex;

  int [ ] data;

  public Sum (int [ ]data, int start, int end) {

  this.data = data;

  this stIndex = start;

  this. lstIndex = end;

  }

  protected void compute ( ) {

  int sum = 0;

  if (lstIndex ?stIndex<;= THRESHOLD_SIZE) {

  for (int i = stIndex; i < lstIndex; i++) {

  sum += data [i];

  }

  System.out.println(sum);

  } else {

  new Sum (data, stIndex + THRESHOLD_SIZE, lstIndex).fork( );

  new Sum (data, stIndex,

  Math.min (lstIndex, stIndex + THRESHOLD_SIZE)

  ).compute ();

  }

  }

  }

  and the code fragment:

  ForkJoinPool fjPool = new ForkJoinPool ( );

  int data [ ] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

  fjPool.invoke (new Sum (data, 0, data.length));

  and given that the sum of all integers from 1 to 10 is 55.

  Which statement is true?

  A. The program prints several values that total 55.

  B. The program prints 55.

  C. A compilation error occurs at line n1.

  D. The program prints several values whose sum exceeds 55.

  Correct Answer: C

• Question 202:

  Given:

  public class Counter {

  public static void main (String[ ] args) {

  int a = 10;

  int b = -1;

  assert (b >=1) : "Invalid Denominator";

  int = a / b;

  System.out.println (c);

  }

  }

  What is the result of running the code with the -ea option?

  A. -10

  B. 0

  C. An AssertionError is thrown.

  D. A compilation error occurs.

  Correct Answer: C

• Question 203:

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

  A. You expect that classes that implement your interfaces have many common methods or fields, or require access modifiers other than public.

  B. You expect that unrelated classes would implement your interfaces.

  C. You want to share code among several closely related classes.

  D. You want to declare non-static on non-final fields.

  E. You want to take advantage of multiple inheritance of type.

  Correct Answer: BE

  Reference: https://books.google.com.br/books?id=nS2tBQAAQBAJandpg=PT235andlpg=PT235anddq=You +want+to+share+code+among+several+closely+related+classes.andsource=blandots=3oYOu2XXNandsig=uVFS0KB15BqyEgghXnnjJSUdcrEandhl=pt-BRandsa=Xandved=0ahUKEwjlsKen6baAhVEhZAKHeiEDTgQ6AEIMDAB#v=onepageandq=You%20want%20to%20share%20code%20among %20several%20closely%20related% 20classes.andf=false

• Question 204:

  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?

  A. Replace line n1 with: IntFunction inFu = x -> y -> x*y;

  B. Replace line n1 with: IntFunction inFu = x -> y -> x*y;

  C. Replace line n1 with: BiFunction inFu = x -> y -> x*y;

  D. Replace line n2 with: IntStream newStream = stream.map(inFu.applyAsInt (10));

  Correct Answer: B

• Question 205:

  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?

  A. 246

  B. The code produces no output.

  C. A compilation error occurs at line n1.

  D. A compilation error occurs at line n2.

  Correct Answer: A

• Question 206:

  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?

  A. A compilation error occurs.

  B. d b e z j

  C. j z e b d

  D. z b d e j

  Correct Answer: C

• Question 207:

  Given the definition of the Vehicle class:

  Class Vehhicle {

  int distance; //line n1

  Vehicle (int x) {

  this distance = x;

  }

  public void increSpeed(int time) { //line n2

  int timeTravel = time; //line n3

  class Car {

  int value = 0;

  public void speed () {

  value = distance /timeTravel;

  System.out.println ("Velocity with new speed"+value+"kmph");

  }

  }

  new Car().speed();

  }

  }

  and this code fragment:

  Vehicle v = new Vehicle (100);

  A. increSpeed(60); What is the result?

  B. Velocity with new speed

  C. A compilation error occurs at line n1.

  D. A compilation error occurs at line n2.

  E. A compilation error occurs at line n3.

  Correct Answer: A