Oracle 1Z0-805 Online Practice Questions and Exam Preparation

Oracle 1Z0-805 Online Questions & Answers

• Question 51:

  Which statement creates a low-overhead, low contention random number generator that is isolated to a thread to generate a random number between 1 and 100?

  A. int i = ThreadLocalRandom.current().nextInt (1, 101);
  B. int i = ThreadSaferandom.current().nextInt(1, 101);
  C. int i = (int) Math.random()*.nextInt(1, 101);
  D. int i = (int) Match.random (1, 101);
  E. int i = new Random (). nextInt (100)+1;
  A. int i = ThreadLocalRandom.current().nextInt (1, 101);

  ---

  public class ThreadLocalRandom extendsRandom A random number generator isolated to the current thread. Like the global Random generator used by the Math class, a ThreadLocalRandom is initialized with an internally generated seed that may not otherwise be modified. When applicable, use ofThreadLocalRandom rather thanshared Random objects in concurrent programs will typically encounter much less overhead and contention. Use of ThreadLocalRandom is particularly appropriate when multiple tasks (for example, each a ForkJoinTask) use random numbers in parallel in thread pools. Usages of this class should typically be of the form: ThreadLocalRandom.current().nextX(...) (where X is Int, Long, etc). When all usages are o this form, it is never possible to accidently share a ThreadLocalRandom across multiple threads. This class also provides additional commonly used bounded random generation methods.

• Question 52:

  Which two statements are true regarding the try with resources statement?

  A. The resources declared in a try with resources statement are not closed automatically if an exception occurs inside the try block.
  B. In a try with resources statement, any catch or finally block is run after the resources have been closed.
  C. The close methods of resources are called in the reverse order of their creation.
  D. All the resources must implement the java.io.closeable interface.
  B. In a try with resources statement, any catch or finally block is run after the resources have been closed.
  D. All the resources must implement the java.io.closeable interface.

  ---

  B: Prior to Java SE 7, you can use a finally block to ensure that a resource is closed regardless of whether the try statement completes normally or abruptly. A try-with-resources statement can have catch and finally blocks just like an ordinary trystateme In a try-with-resources statement, any catch or finally block is run after the resources declared have been closed.

  D:The try-with-resources statement is a try statement that declares one or more resources. Aresource is an object that must be closed after the program is finished with it. The try-with- resources statement ensures that each resource is closed at the end of the statement. Any object that implements java.lang.AutoCloseable, which includes all objects which implementjava.io.Closeable, can be used as a resource.

  Reference: The Java Tutorials,The try-with-resources Statement

• Question 53:

  Given the code fragment:

  private static void copyContents (File source, File target) {

  try {inputStream fis = new FileInputStream(source);

  outputStream fos = new FileOutputStream (target);

  byte [] buf = new byte [8192]; int i;

  while ((i = fis.read(buf)) != -1) {

  fos.write (buf, 0, i);

  }

  //insert code fragment here. Line **

  System.out.println ("Successfully copied");

  }

  Which code fragments, when inserted independently at line **, enable the code to compile?

  A. }catch (IOException | NoSuchFileException e) { System.out.println(e); }
  B. } catch (IOException | IndexOutOfBoundException e) { System.out.println(e); }
  C. } catch (Exception | IOException | FileNotFoundException e ) { System.out.println(e); }
  D. } catch (NoSuchFileException e ) { System.out.println(e); }
  E. } catch (InvalidPathException | IOException e) { System.out.println(e); }
  B. } catch (IOException | IndexOutOfBoundException e) { System.out.println(e); }
  D. } catch (NoSuchFileException e ) { System.out.println(e); }
  E. } catch (InvalidPathException | IOException e) { System.out.println(e); }

  ---

  B: Two mutually exclusive exceptions. Will work fine.

  D: A single exception. Will work fine.

  E: Two mutually exclusive exceptions. Will work fine.

  Note: In Java SE 7 and later, a single catch block can handle more than one type of exception. This feature can reduce code duplication and lessen the temptation to catch an overly broad exception.

  In the catch clause, specify the types of exceptions that block can handle, and separate each exception type with a vertical bar (|).

  Note 2:NoSuchFileException: Checked exception thrown when an attempt is made to access a file that does not exist.

  InvalidPathException: Unchecked exception thrown when path string cannot be converted into a Path because the path string contains invalid characters, or the path string is invalid for other file system specific reasons.

  FileNotFoundException: Signals that an attempt to open the file denoted by a specified pathname has failed.

  This exception will be thrown by the FileInputStream, FileOutputStream, and RandomAccessFile constructors when a file with the specified pathname does not exist. It will also be thrown by these constructors if the file does exist but for some

  reason is inaccessible, for example when an attempt is made to open a read-only file for writing.

• Question 54:

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

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

  ---

  The java.util.concurrent package defines three executor interfaces:

  *(F)Executor, a simple interface that supports launching new tasks. *(A)ExecutorService, a subinterface of Executor, which adds features that help manage the lifecycle, both of the individual tasks and of the executor itself.

  * ScheduledExecutorService, a subinterface of ExecutorService, supports future and/or periodic execution of tasks.

  Typically, variables that refer to executor objects are declared as one of these three interface types, not with an executor class type.

  D: The ExecutorService interface supplements execute with a similar, but more versatile submit method. Like execute, submit accepts Runnable objects, but also accepts Callable objects, which allow the task to return a value.

  Reference: The Java Tutorials,Executor Interfaces

• Question 55:

  Which three objects must a vendor provide implementations in its JDBC driver?

  A. Time
  B. Date
  C. Statement
  D. RuleSet
  E. Connection
  F. SQLException
  G. DriverManager
  E. Connection
  F. SQLException
  G. DriverManager

  ---

  E:When the method getConnection is called, the DriverManager will attempt to locate a suitable driver from amongst those loaded at initialization and those loaded explicitly using the same classloader as the current applet or application.

  F: An SQLException is an exception that provides information on a database access error or other errors.

  G: DriverManager is the basic service for managing a set of JDBC drivers. Reference: The Java Tutorials,Class DriverManager

• Question 56:

  You have been asked to create a ResourceBundle file to localize an application.

  Which code example specifies valid keys of menu1 and menu2 with values of File Menu and View Menu?

  A. File Menu view Menu
  B. menu1File Menu menu2View Menu
  C. menu1, File Menu, menu2, View Menu
  D. menu1 = File Menu menu2 = View Menu
  D. menu1 = File Menu menu2 = View Menu

  ---

  A properties file is a simple text file. You can create and maintain a properties file with just about any text editor.

  You should always create a default properties file. The name of this file begins with the base name of your ResourceBundle and ends with the .properties suffix.

  An example of the contents of a ResourceBundle file:

  # This is a comment s1 = computer s2 = disk s3 = monitor s4 = keyboard

  Note that in the preceding file the comment lines begin with a pound sign (#). The other lines contain key-value pairs. The key is on the left side of the equal sign and the value is on the right. For instance, s2 is the key that corresponds to the value disk. The key is arbitrary. We could have called s2 something else, like msg5 or diskID. Once defined, however, the key should not change because it is referenced in the source code. The values may be changed. In fact, when your localizers create new properties files to accommodate additional languages, they will translate the values into various languages.

  Reference: The Java Tutorials, Backing a ResourceBundle with Properties Files

• Question 57:

  Given the code fragment:

  /* method declaration */ {

  try {

  String className = "java.lang.String";

  String fieldname = "somefield";

  Class c = Class.forName(className);

  Field f = c.getField(fieldname);

  } catch(Exception e)

  { e.printStackTrace();

  throw e;

  }

  }

  Which two method declarations are valid options to replace /* method declaration */?

  A. public void getMetadata ()
  B. public void getMetadat ()
  C. public void getMetadata () throws Exception
  D. public void getMetadata () throws NoSuchFieldException
  E. public void getMetadata () throws classNotFoundException
  F. public void getMetadata () throws ClassNotFoundException, NoSuchFieldException.
  C. public void getMetadata () throws Exception
  E. public void getMetadata () throws classNotFoundException

  ---

  We must specify that the getMetaData method can throw both ClassNotFoundException (line Class c = Class.forName(className);) and a NoSuchFieldException (line Field f = c.getField(fieldname);). We can do this by either declare that all exception can be thrown or that these two specific exceptions can be thrown

  Note: Valid Java programming language code must honor the Catch or Specify Requirement. This means that code that might throw certain exceptions must be enclosed by either of the following:

  *

  A try statement that catches the exception. The try must provide a handler for the exception.

  *

  A method that specifies that it can throw the exception. The method must provide a throws clause that lists the exception. Code that fails to honor the Catch or Specify Requirement will not compile.

  Reference: The Java Tutorials, The Catch or Specify Requirement

• Question 58:

  Given:

  private static void copyContents() {

  try (

  InputStream fis = new FileInputStream("report1.txt");

  OutputStream fos = new FileOutputStream("consolidate.txt");

  ) {

  byte[] buf = new byte[8192];

  int i;

  while ((i = fis.read(buf)) != -1) {

  fos.write(buf, 0, i);

  }

  fis.close();

  fis = new FileInputStream("report2.txt");

  while ((i = fis.read(buf)) != -1) {

  fos.write(buf, 0, i);

  }

  }

  What is the result?

  A. Compilation fails due to an error at line 28
  B. Compilation fails due to error at line 15 and 16
  C. The contents of report1.txt are copied to consolidate.txt. The contents of report2.txt are appended to consolidate.txt, after a new line
  D. The contents of report1.txt are copied to consolidate.txt. The contents of report2.txt are appended to consolidate.txt, without a break in the flow.
  A. Compilation fails due to an error at line 28

  ---

  The auto-closable resource fis may not be assigned.

  Note: The try-with-resources statement is a try statement that declares one or more resources. A resource is an object that must be closed after the program is finished with it. The try-with- resources statement ensures that each resource is closed at the end of the statement. Any object that implements java.lang.AutoCloseable, which includes all objects which implement java.io.Closeable, can be used as a resource. Reference: The Java Tutorials,The try-with-resources Statement

• Question 59:

  Given the code fragment:

  SimpleDateFormat sdf;

  Which code fragment displays the two-digit month number?

  A. sdf = new SimpleDateFormat ("mm", Locale.UK); System.out.printIn ( "Result: " + sdf.format(new Date()))
  B. sdf = new SimpleDateFormat ("MM", Locale.UK); System.out.printIn ( "Result: " + sdf.format(new Date()))
  C. sdf = new SimpleDateFormat ("MMM", Locale.UK); System.out.printIn ( "Result: "+ sdf.format(new Date()))
  D. sdf = new SimpleDateFormat ("MMMM", Locale.UK); System.out.printIn ("Result:"+ sdf.format(new Date()))
  B. sdf = new SimpleDateFormat ("MM", Locale.UK); System.out.printIn ( "Result: " + sdf.format(new Date()))

  ---

  B: Output example (displays current month numerically): 04

  Note:SimpleDateFormat is a concrete class for formatting and parsing dates in a locale-sensitive manner. It allows for formatting (date -> text), parsing (text -> date), and normalization. SimpleDateFormat allows you to start by choosing any user-defined patterns for date-time formatting. However, you are encouraged to create a date-time formatter with either getTimeInstance, getDateInstance, orgetDateTimeInstance in DateFormat. Each of these class methods can return a date/time formatter initialized with a default format pattern. You may modify the format pattern using the applyPattern methods as desired.

• Question 60:

  Given the code format:

  SimpleDateFormat sdf;

  Which code statements will display the full text month name?

  A. sdf = new SimpleDateFormat ("mm", Locale.UK); System.out.println ( "Result: " + sdf.format(new Date()));
  B. sdf = new SimpleDateFormat ("MM", Locale.UK); System.out.println ("Result:"+ sdf.format(new Date()));
  C. sdf = new SimpleDateFormat ("MMM", Locale.UK); System.out.println ("Result:"+ sdf.format(new Date()));
  D. sdf = new SimpleDateFormat ("MMMM", Locale.UK); System.out.println ("Result:"+ sdf.format(new Date()));
  D. sdf = new SimpleDateFormat ("MMMM", Locale.UK); System.out.println ("Result:"+ sdf.format(new Date()));

  ---

  To getthe full length month name use SimpleDateFormat('MMMM'). Note:SimpleDateFormat is a concrete class for formatting and parsing dates in a locale-sensitive manner. It allows for formatting (date -> text), parsing (text -> date), and normalization. SimpleDateFormat allows you to start by choosing any user-defined patterns for date-time formatting. However, you are encouraged to create a date-time formatter with either getTimeInstance, getDateInstance, orgetDateTimeInstance in DateFormat. Each of these class methods can return a date/time formatter initialized with a default format pattern. You may modify the format pattern using the applyPattern methods as desired.