Oracle 1Z0-804 Online Practice Questions and Exam Preparation

Oracle 1Z0-804 Online Questions & Answers

• Question 11:

  Which method would you supply to a class implementing the Callable interface?

  A. callable ()
  B. executable ()
  C. call ()
  D. run ()
  E. start ()
  C. call ()

  ---

  public interface Callable

  A task that returns a result and may throw an exception. Implementors define a single method with no arguments called call.

  Note:

  Interface Callable

  Type Parameters:

  V - the result type of method call

  The Callable interface is similar to Runnable, in that both are designed for classes whose instances are potentially executed by another thread. A Runnable, however, does not return a result and cannot throw a checked exception.

  The Executors class contains utility methods to convert from other common forms to Callable classes.

  Reference: java.util.concurrent

• Question 12:

  Given the code fragment:

  public class ReadFile01 {

  public static void main(String[] args) {

  String fileName = "myfile.txt";

  try (BufferedReader buffIn = // Line 4

  new BufferedReader(new FileReader(fileName))) {

  String line = ""; int count = 1;

  line = buffIn.readLine(); // Line 7

  do {

  line = buffIn.readLine();

  System.out.println(count + ": " + line);

  } while (line != null);

  } catch (IOException | FileNotFoundException e) {

  System.out.println("Exception: " + e.getMessage()); } } } What is the result, if the file myfile.txt does not exist?

  A. A runtime exception is thrown at line 4
  B. A runtime exception is thrown at line 7
  C. Creates a new file and prints no output
  D. Compilation fails
  A. A runtime exception is thrown at line 4

  ---

  There will be a FileNotFoundException at line 4.

• Question 13:

  Which code fragment demonstrates the proper way to handle JDBC resources?

  A. Try { ResultSet rs = stmt.executableQuery (query); statement stmt = con.createStatement(); while (rs.next()) (/* . . . */) } catch (SQLException e) {}
  B. Try {statement stmt = con.createStatement(); ResultSet rs = stmt.executableQuery (query); while (rs.next()) (/* . . . */) } catch (SQLException e) {}
  C. Try { statement stmt = con.createStatement(); ResultSet rs = stmt.executableQuery (query); while (rs.next()) (/* . . . */) } finally { rs.close(); stmt.close(); }
  D. Try { ResultSet rs = stmt.executableQuery (query); statement stmt = con.createStatement(); while (rs.next()) (/* . . . */) } finally { rs.close(); stmt.close(); }
  C. Try { statement stmt = con.createStatement(); ResultSet rs = stmt.executableQuery (query); while (rs.next()) (/* . . . */) } finally { rs.close(); stmt.close(); }

  ---

  We should use the finally statement to gracefully close the connection.

• Question 14:

  Given three resources bundles with these values set for menu1: (the default resource bundle in US English.)

  English US Resource Bundle

  Menu1 = small

  French Resource Bundle

  Menu1 = petit

  Chinese Resource Bundle

  Menu1 =

  And given the code fragment:

  Locale.setDefault(new Locale("es", "ES")); // Set default to Spanish and Spain

  Locale loc1 = Locale.getDefault();

  ResourceBundle message = ResourceBundle.getBundle("MessageBundle", loc1);

  System.out.println(message.getString("menu1"));

  What is the result?

  A. No message is printed
  B. Petit C.
  D. A runtime error is produced
  D. A runtime error is produced

  ---

  There is no Spanish resource bundle. The following runtime error will occur:

  Exception in thread "main" java.util.MissingResourceException: Can't find bundle for base name MessageBundle, locale es_ES

• Question 15:

  Given the code fragment:

  public class Base {

  BufferedReader br;

  String record;

  public void process() throws FileNotFoundException {

  br = new BufferedReader(new FileReader("manual.txt"));

  }

  }

  public class Derived extends Base {

  // insert code here. Line ***

  public static void main(String[] args) {

  try {

  new Derived().process();

  } catch (Exception e) { } }

  }

  Which code fragment inserted at line ***, enables the code to compile?

  A. public void process () throws FileNotFoundException, IOException { super.process (); while ((record = br.readLine()) != null) { System.out.println(record); } }
  B. public void process () throws IOException { super.process (); while ((record = br.readLine()) != null) { System.out.println(record); } }
  C. public void process () throws Exception { super.process (); while ((record = br.readLine()) != null) { System.out.println(record); } }
  D. public void process (){ try { super.process (); while ((record = br.readLine()) != null) { System.out.println(record); } } catch (IOException | FileNotFoundException e) { } }
  E. public void process (){ try { super.process (); while ((record = br.readLine()) != null) { System.out.println(record); } } catch (IOException e) {} }
  E. public void process (){ try { super.process (); while ((record = br.readLine()) != null) { System.out.println(record); } } catch (IOException e) {} }

  ---

  Incorrect answer:

  D: exception java.io.FileNotFoundException has already been caught

  Alternatives in a multi-catch statement cannot be related to subclassing Alternative java.io. FileNotFoundException is a subclass of alternative java.io.IOException

• Question 16:

  Given the cache class:

  public class Cache {

  private T t;

  public void setValue (T t) { this.t=t; }

  public T getValue() {return t; }

  }

  What is the result of the following?

  Cache<> c = new Cache(); // Line 1

  A. SetValue(100); // Line 2 System.out.print(c.getValue().intValue() +1); // Line 3
  B. 101
  C. Compilation fails at line 1.
  D. Compilation fails at line 2.
  E. Compilation fails at line 3.
  B. 101

  ---

  Compilation failure at line:

  illegal start of type type cache.Cache does not take parameters.

• Question 17:

  Which type of ExecutorService supports the execution of tasks after a fixed delay?

  A. DelayedExecutorService
  B. ScheduledExecutorService
  C. TimedExecutorService
  D. FixedExecutorService
  E. FutureExecutorService
  B. ScheduledExecutorService

  ---

  The ScheduledExecutorService interface supplements the methods of its parent ExecutorService with schedule, which executes a Runnable or Callable task after a specified delay. In addition, the interface defines scheduleAtFixedRate and scheduleWithFixedDelay, which executes specified tasks repeatedly, at defined intervals.

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

  *

  Executor, a simple interface that supports launching new tasks.

  *

  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.

  Reference: The Java Tutorials, Executor Interfaces

• Question 18:

  Which three statements are correct about thread's sleep method?

  A. The sleep (long) method parameter defines a delay in milliseconds.
  B. The sloop (long) method parameter defines a delay in microseconds.
  C. A thread is guaranteed to continue execution after the exact amount of time defined in the sleep (long) parameter.
  D. A thread can continue execution before the amount of time defined in the sleep (long) parameter.
  E. A thread can continue execution after the amount of time defined in the sleep(long) parameter
  F. Only runtime exceptions are thrown by the sleep method.
  G. A thread loses all object monitors (lock flags) when calling the sleep method.
  A. The sleep (long) method parameter defines a delay in milliseconds.
  C. A thread is guaranteed to continue execution after the exact amount of time defined in the sleep (long) parameter.
  E. A thread can continue execution after the amount of time defined in the sleep(long) parameter

  ---

  public static void sleep(long millis)

  throws InterruptedException

  Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds (A, not B). The thread does not lose ownership of any monitors (not G).

  Parameters:

  millis - the length of time to sleep in milliseconds.

  Throws:

  InterruptedException - if another thread has interrupted the current thread. The interrupted status of the current thread is cleared when this exception is thrown.

• Question 19:

  Given:

  class A {

  int a = 5;

  String doA() { return "a1"; }

  protected static String doA2 () { return "a2"; }

  }

  class B extends A {

  int a = 7;

  String doA() { return "b1"; }

  public static String doA2() { return "b2"; }

  void go() {

  A myA = new B();

  System.out.print(myA.doA() + myA.doA2() + myA.a);

  }

  public static void main (String[] args) { new B().go(); }

  }

  Which three values will appear in the output?

  A. 5
  B. 7
  C. a1
  D. a2
  E. b1
  F. b2
  B. 7
  E. b1
  F. b2

• Question 20:

  Given:

  interface Books {

  //insert code here

  }

  Which fragment, inserted in the Books interface, enables the code to compile?

  A. public abstract String type; public abstract String getType();
  B. public static String type; public abstract String getType();
  C. public String type = "Fiction"; public static String getType();
  D. public String type = "Fiction"; public abstract String getType();
  D. public String type = "Fiction"; public abstract String getType();