Oracle 1Z0-813 Online Practice Questions and Exam Preparation

Oracle 1Z0-813 Online Questions & Answers

• Question 31:

  Given the code fragment:

  

  Which is the valid definition for the Greeter interface to enable the code fragment to print Kathy Welcome!?

  

  A. Option A
  B. Option B
  C. Option C
  D. Option D
  A. Option A

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  Code example works fine:

  

• Question 32:

  Which two statements are true about the walkFileTree method of the Files class? (Choose two.)

  A. By default, symbolic links are not automatically followed by this method.
  B. The maxDepth parameter's value is the maximum number of directories to visit.
  C. If the file is a directory, and if that directory could not be opened, the portVisitDirectory method is invoked with the I/O exception.
  D. The file tree traversal is breadth-first with the given FileVisitor invoked for each file encountered.
  E. If the file attributes cannot be read due to an I/O exception, the visitFileFailed method is invoked with the I/O exception.
  A. By default, symbolic links are not automatically followed by this method.
  E. If the file attributes cannot be read due to an I/O exception, the visitFileFailed method is invoked with the I/O exception.

  ---

  By default, symbolic links are not automatically followed by this method.

  For each file encountered this method attempts to read its BasicFileAttributes. If the file is not a directory then the visitFile method is invoked with the file attributes. If the file attributes cannot be read, due to an I/O exception, then the

  visitFileFailed method is invoked with the I/O exception.

  Incorrect Answers:

  B: maxDepth is the maximum number of directory levels to visit.

  C: Where the file is a directory, and the directory could not be opened, then the visitFileFailed method is invoked with the I/O exception, after which, the file tree walk continues, by default, at the next sibling of the directory.

  D: The file tree traversal is depth-first.

  Reference: https://docs.oracle.com/javase/7/docs/api/java/nio/file/Files.html

• Question 33:

  Given:

  

  What is the result?

  A. 0 1 4 3 4
  B. 0 1 2 3 4
  C. 1 2 3 4 5
  D. 1 1 1 1 1
  D. 1 1 1 1 1

• Question 34:

  Which three must be used when using the java.util.concurrent package to execute a task that returns a result without blocking? (Choose three.)

  A. Executor
  B. Callable
  C. Future
  D. ExecutorService
  E. Runnable
  F. Thread
  A. Executor
  B. Callable
  F. Thread

  ---

  AB: we can implement a Callback interface if we want our Executor to be notified without blocking that a task has completed.

  F: A task (thread) is non-blocking when it doesn't cause other tasks (threads) to wait until the task is finished.

  B: A callable interface is a task that returns a result and may throw an exception.

  The Callable interface is similar to Runnable, in that both are designed for classes whose instances are potentially executed by another thread.

  Incorrect Answers:

  E: A Runnable interface does not return a result and cannot throw a checked exception.

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

• Question 35:

  Given the code fragment:

  

  What change must you make to enable the code to print the following output? 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

  A. Replace line 8 with .peek(e -> { myList.add(e); }).
  B. Replace line 7 with .stream().
  C. Replace line 12 with .parallelStream().
  D. Replace line 13 with .forEachOrdered(e -> System.out.print(e + " "));.
  B. Replace line 7 with .stream().

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  Incorrect Answers:

  A: Uncompilable source code - Erroneous sym type at line forEachOrdered(e -> System.out.print(e + " "));

• Question 36:

  Given the interface:

  

  Which class implements idGenerator in a safe manager, so that no threads can get a duplicate id value during concurrent access?

  A. public class Generator implements IdGenerator ( Private volatile int Id -0; Public int getNExt Td() | Synchronized (new generator()) { return ++id; } } }
  B. public class Generator implements IdGeneretor ( Private int id =0; Public int getNExtId {) { Synchronized (new generator()) {
  C. return ++id; } } }
  D. public Class Generator implement IdGenerator ( privateAtcmicinInteger id - new AtomaticIntegger (0); public int getNextId{} { return id. Increaseincrasement AndSet{) ; } }
  E. public Class Generator implement IdGenerator ( Private int id =0; Public int getNextId { ) { Synchronized (id) ; return ++id } }
  F. public Class Generator implement IdGenerator ( Private int id =0; Public int getNextId { ) { Synchronized (id) ; return ++id } } } Return ++id;
  C. return ++id; } } }

• Question 37:

  Given the code fragment:

  

  Which two code fragments, when inserted independently at line 14, enable the code to compile? (Choose two.)

  A. Map category = new HashMap();
  B. Map category = new HashMap();
  C. Map category = new HashMap();
  D. Map category = new HashMap();
  E. Map category = new HashMap();
  F. Map category = new HashMap();
  D. Map category = new HashMap();
  F. Map category = new HashMap();

• Question 38:

  Given the directory structure:

  

  Given the code fragment:

  

  Which code fragment, when inserted at line n1, produces the result fy2014.txt?

  A. Stream files = Files.walk(Paths.get("D:\\report"));
  B. Stream files = Files.walk(Paths.get("D:\\report"), 3, (p, a) -> p.isRegularFile());
  C. Stream files = Files.find(Paths.get("D:\\report\\fy2014.txt'));
  D. Stream files = Files.walk(Paths.get("D:\\report"), 3, (p, a) -> a.isRegularFile());
  C. Stream files = Files.find(Paths.get("D:\\report\\fy2014.txt'));

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  Incorrect Answers:

  A: Output: reportfy2014.txt

• Question 39:

  Given the code fragment:

  

  You have been asked to define the ProductCode class. The definition of the ProductCode class must allow c1 instantiation to succeed and cause a compilation error on c2 instantiation.

  Which definition of ProductCode meets the requirement?

  A. class ProductCode { T c1; S c2; }
  B. class ProductCode { T c1; S c2; }
  C. class ProductCode { T c1; S c2; }
  D. class ProductCode { T c1; S c2; }
  B. class ProductCode { T c1; S c2; }

• Question 40:

  Given the code fragment:

  

  If exceptions occur when closing the FileWriter object and when retrieving the JString class object, which exception object is propagated up to the caller of the processFile method?

  A. java.lang.Exception
  B. java.io.IOException
  C. java.lang.ClassNotFoundException
  D. java.lang.NoSuchClassException
  C. java.lang.ClassNotFoundException

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  ClassNotFoundException is thrown when an application tries to load in a class through its string name using:

  *

  The forName method in class Class.

  *

  The findSystemClass method in class ClassLoader .

  *

  The loadClass method in class ClassLoader.

  but no definition for the class with the specified name could be found.

  References: https://docs.oracle.com/javase/7/docs/api/java/lang/ClassNotFoundException.html