Oracle 1Z0-813 Online Practice Questions and Exam Preparation

Oracle 1Z0-813 Online Questions & Answers

• Question 21:

  Given the following incorrect program:

  

  Which two changes make the program work correctly? (Choose two.)

  A. The MyTask class must be modified to extend RecursiveAction instead of RecursiveTask.
  B. The computeDirectly() method must be enhanced to fork() newly created tasks.
  C. The compute() method must be changed to return an Integer result.
  D. The THRESHOLD value must be increased so that the overhead of task creation does not dominate the cost of computation.
  E. Results must be retrieved from the newly created MyTask instances and combined.
  F. The midpoint computation must be altered so that it splits the workload in an optimal manner.
  C. The compute() method must be changed to return an Integer result.
  E. Results must be retrieved from the newly created MyTask instances and combined.

  ---

  The compute() method must return an Integer result. The results of the InvokeAll tasks must be combined.

  Incorrect Answers:

  A: RecursiveAction is just like RecursiveTask except it does not return a result

  F: The Midpoint, mid = (low + high)/2, is fine. Reference: http://www.baeldung.com/java-fork-join

• Question 22:

  Given the code fragments:

  

  and

  

  What is the result?

  A. Java SE:2000.0 Java ME:120.0
  B. Java SE:300.0 Java ME:120.0
  C. Compilation fails due to an error at line 15.
  D. Compilation fails due to an error at line 16.
  D. Compilation fails due to an error at line 16.

  ---

  Uncompilable source code - Erroneous tree type: at line: books.forEach(b -> System.out.println(b.name + ":" + b.price));

  To make the code compile we would change the name reference to bname: books.forEach(b -> System.out.println(b.bname + ":" + b.price));

  Note: To make the code work we would need etter and getter methods:

  

• Question 23:

  Given the code fragment:

  

  What is the result?

  A. A compilation error occurs.
  B. An IllegalStateException is thrown at run time.
  C. Tom, Hello Joe, Hello
  D. Tom, Joe,
  C. Tom, Hello Joe, Hello

  ---

  Output: Tom,Hello Joe,Hello

• Question 24:

  Given:

  

  and the code fragment:

  

  You have been asked to ensure that the run methods of both the Worker and the Master classes are executed. Which modification meets the requirement?

  A. At line n2, insert CyclicBarrier cb = new CyclicBarrier(master);
  B. At line n2, insert CyclicBarrier cb = new CyclicBarrier(1);
  C. At line n2, insert CyclicBarrier cb = new CyclicBarrier(2, master);
  D. At line n2, insert CyclicBarrier cb = new CyclicBarrier(1, master);
  D. At line n2, insert CyclicBarrier cb = new CyclicBarrier(1, master);

  ---

  

  Creates a new CyclicBarrier that will trip when the given number of parties (threads) are waiting upon it, and which will execute the given barrier action when the barrier is tripped, performed by the last thread entering the barrier.

  Parameters:

  parties - the number of threads that must invoke await() before the barrier is tripped

  barrierAction - the command to execute when the barrier is tripped, or null if there is no action

  Reference: https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/CyclicBarrier.html

• Question 25:

  Given the code fragment:

  

  and

  

  Which code fragment could you see to refactor the code from line 4 to 8 to use a Lambda expression?

  A. Vehicle v = new Vehicle(int speed) { System.out.print("Fly at " + speed); );
  B. Vehicle v = int speed -> System.out.print("Fly at " + speed);
  C. Vehicle v = (int speed) -> System.out.print("Fly at " + speed);
  D. Vehicle v = speed -> {System.out.print("Fly at " + speed) };
  C. Vehicle v = (int speed) -> System.out.print("Fly at " + speed);

• Question 26:

  Given:

  

  and the code fragment:

  

  What is the result?

  A. [Java EE:Helen:Houston] [Java ME:Jessy:Chicago, Java ME: Mark:Chicago]
  B. Java EE Java ME
  C. [Java ME:Jessy:Chicago, Java ME:Mark:Chicago] [Java EE:Helen:Houston]
  D. A compilation error occurs.
  B. Java EE Java ME

  ---

  Grouping on course. Print each course.

• Question 27:

  Given the code fragment:

  

  What is the result?

  A. [x, x] [x, x, x, x]
  B. [x] [x, x] [x, x, x]
  C. [x] [x, x] [x, x, x] [x, x, x, x]
  D. [x, x]
  A. [x, x] [x, x, x, x]

• Question 28:

  Given the code fragment:

  

  What type of result is printed?

  A. Time of the Epoch (in milliseconds)
  B. Julian date
  C. Era
  D. Time zone abbreviation
  E. Full-text time zone name
  E. Full-text time zone name

  ---

  Output could be:

  Result: Central European Time

  Note: To make the code work you would need the following code which get today's date in Java.

  Date today = new Date();

  Reference: http://www.java67.com/2013/01/how-to-format-date-in-java-simpledateformat-example.html

• Question 29:

  Which statement is true about java.util.stream.Stream?

  A. All Stream operations are lazy.
  B. Objects in streams are intended to be mutable.
  C. Streams support aggregate operations.
  D. Streams can be reused.
  C. Streams support aggregate operations.

• Question 30:

  Given the code fragment:

  

  Assume that the Pics directory does NOT exist. What is the result?

  A. 1:Pics:/Pics/MyPic.jpeg
  B. An exception is thrown at run time.
  C. 2:MyPic.jpeg:MyPic.jpeg
  D. 2:Pics:MyPic.jpeg
  C. 2:MyPic.jpeg:MyPic.jpeg