Oracle 1Z0-804 Online Practice Questions and Exam Preparation

Oracle 1Z0-804 Online Questions & Answers

• Question 111:

  Given the integer implements comparable:

  import java.util.*;

  public class SortAndSearch2 {

  static final Comparator IntegerComparator =

  new Comparator() {

  public int compare (Integer n1, Integer n2) {

  return n2.compareTo(n1);

  }

  };

  public static void main(String args[]) {

  ArrayList list = new ArrayList<>();

  list.add (4);

  list.add (1);

  list.add (3);

  list.add (2);

  Collections.sort(list, null);

  System.out.println(Collections.binarySearch(list, 3));

  Collections.sort(list,IntegerComparator);

  System.out.println(Collections.binarySearch(list, 3));

  }

  }

  What is the result?

  A. 2
  B. 1
  C. 2
  D. 2
  E. 3
  A. 2

• Question 112:

  Given:

  public class Counter {

  public static int getCount(String[] arr) {

  int count =0 ;

  for(String var:arr) {

  if(var!=null) count++;

  }

  return count;

  }

  public static void main(String[] args) {

  String[] arr =new String[4];

  arr[1] = "C";

  arr[2] = "";

  arr[3] = "Java";

  assert (getCount(arr) < arr.length);

  System.out.print(getCount(arr));

  }

  }

  And the commands:

  javac Counter.java

  java -ea Counter

  What is the result?

  A. 2
  B. 3
  C. NullPointException is thrown at runtime
  D. AssertionError is thrown at runtime
  E. Compilation fails
  D. AssertionError is thrown at runtime

  ---

  The command line javac Counter.java

  will compile the code.

  The command line java -ea Counter

  will run the cod with assertions enabled.

  The following line:

  assert (getCount(arr) < arr.length);

  where the Boolean expression getCount(arr) < arr.length will evaluate to false, will ensure that an AssertionError is thrown at runtime.

  Note: The javac command compiles Java source code into Java bytecodes. You then use the Java interpreter - the java command - to interprete the Java bytecodes.

  Note 2: The java tool launches a Java application. It does this by starting a Java runtime environment, loading a specified class, and invoking that class's main method. The method declaration must look like the following:

  public static void main(String args[])

  Paramater -ea:

  -enableassertions[:"..." | : ]

  -ea[:"..." | : ]

  Enable assertions. Assertions are disabled by default.

  With no arguments, enableassertions or -ea enables assertions.

  Note 3:

  An assertion is a statement in the JavaTM programming language that enables you to test your assumptions about your program.

  Each assertion contains a boolean expression that you believe will be true when the assertion executes. If it is not true, the system will throw an error.

• Question 113:

  Given:

  abstract class Boat {

  String doFloat() { return "floating"; }

  abstract void doDock();

  }

  class Sailboat extends Boat {

  public static void main(String[] args) {

  Boat b = new Sailboat(); // Line A

  Boat b2 = new Boat(); // Line B

  }

  String doFloat() { return "slow float"; } // Line C

  void doDock() { } // Line D

  }

  Which two are true about the lines labeled A through D?

  A. The code compiles and runs as is.
  B. If only line A is removed, the code will compile and run.
  C. If only line B is removed, the code will compile and run.
  D. If only line D is removed, the code will compile and run.
  E. Line C is optional to allow the code to compile and run.
  F. Line C is mandatory to allow the code to compile and run.
  A. The code compiles and runs as is.
  E. Line C is optional to allow the code to compile and run.

  ---

  A: The code will compile. The abstract method doDock() is implemented fine, and doFloat() is overridden.

  E: Line C overrides the implementation of doFloat(). This is optional.

• Question 114:

  Given a language code of fr and a country code of FR, which file name represents a rce bundle file name that is not the default?

  A. MessageBundle_fr_FR.properties
  B. MessageBundle_fr_FR.profile
  C. MessageBundle_fr_FR.xinl
  D. MessageBundle__fr__FR.Java
  E. MessageBundle__fr__FR.Locale
  A. MessageBundle_fr_FR.properties

  ---

  The default file is MessageBundle.properties.

  The non-default file name is MessageBundle_fr_FR.properties

  Note 0: .properties is a file extension for files mainly used in Java related technologies to store the configurable parameters of an application. They can also be used for storing strings for Internationalization and localization; these are known

  as Property Resource Bundles.

  Each parameter is stored as a pair of strings, one storing the name of the parameter (called the key), and the other storing the value.

  Note 1: You can obtain an instance of ResourceBundle by calling its static getBundle method.

  public static ResourceBundle getBundle(java.lang.String baseName)

  public static ResourceBundle getBundle(java.lang.String baseName, Locale locale)

  For example:

  ResourceBundle rb = ResourceBundle.getBundle("MyResources", Locale.US);

  This will load the ResourceBundle object with the values in the corresponding properties file.

  1.

  If a suitable properties file is not found, the ResourceBundle object will use the default properties file, which will be the one whose name equals the base name and has the properties extension. In this case, the default file would be MyResources.properties.

  2.

  If this file is not found, a java.util.MissingResourceException will be thrown.

  Note 2: java.util.ResourceBundle class enables you to choose and read the properties file specific to the user's locale and look up the values.

  A ResourceBundle object has a base name. In order for a ResourceBundle object to pick up a properties file, the filename must be composed of the ResourceBundle base name, followed by an underscore, followed by the language code,

  and optionally followed by another underscore and the country code.

  The format for the properties file name is as follows:

  basename_languageCode_countryCode

  For example, suppose the base name is MyResources and you define the following three locales:

  US-en

  DE-de

  CN-zh

  Then you would have these three properties files:

  MyResources_en_US.properties

  MyResources_de_DE.properties

  MyResources_zh_CN.properties

  Reference: Reading Properties Files using ResourceBundle

• Question 115:

  Which is a factory method from the java.text.NumberFormat class?

  A. format (long number)
  B. getInstance()
  C. getMaxiraumFractionDigits ()
  D. getAvailableLocales ()
  E. isGroupingUsed()
  B. getInstance()

  ---

  To obtain a NumberFormat for a specific locale, including the default locale, call one of NumberFormat's factory methods, such as getInstance(). Reference: java.text Class DecimalFormat

• Question 116:

  Which four are true about enums?

  A. An enum is typesafe.
  B. An enum cannot have public methods or fields.
  C. An enum can declare a private constructor.
  D. All enums implicitly implement Comparable.
  E. An enum can subclass another enum.
  F. An enum can implement an interface.
  A. An enum is typesafe.
  C. An enum can declare a private constructor.
  D. All enums implicitly implement Comparable.
  F. An enum can implement an interface.

  ---

  C: The constructor for an enum type must be package-private or private access. Reference: Java Tutorials, Enum Types

• Question 117:

  Given:

  import java.util.Scanner;

  public class Painting {

  public static void main(String[] args) {

  String input = "Pastel, *Enamel, Fresco, *Gouache";

  Scanner s = new Scanner(input);

  A. useDelimiter(",\\s*"); while (s.hasNext()) { System.out.println(s.next()); } } } What is the result?
  B. Paste1 Ename1 Fresco Gouache
  C. Paste1 *Ename1 Fresco *Gouache
  D. Pastel Ename1 Fresco Gouache
  E. Pastel Ename1, Fresco Gouache
  B. Paste1 Ename1 Fresco Gouache

• Question 118:

  Given:

  

  Which group of method is moved to a new class when implementing the DAO pattern?

  A. public in getId () public String getContractDetails () public Void setContractDetails(String contactDetails) public String getName () public void setName (String name)
  B. public int getId () public String getContractDetails() public String getName() public Person getPerson(int id) throws Exception
  C. public void setContractDetails(String contractDetails) public void setName(String name)
  D. public Person getPerson(int id) throws Exception public void createPerson(Person p) throws Exception public void deletePerson(int id) throws Exception public void updatePerson(Person p) throws Exception
  D. public Person getPerson(int id) throws Exception public void createPerson(Person p) throws Exception public void deletePerson(int id) throws Exception public void updatePerson(Person p) throws Exception

  ---

  The methods related directly to the entity Person is moved to a new class.

  Note: DAO Design Pattern

  *

  Abstracts and encapsulates all access to a data source

  *

  Manages the connection to the data source to obtain and store data

  *

  Makes the code independent of the data sources and data vendors (e.g. plain-text, xml, LDAP, MySQL, Oracle, DB2)

  

  Example (here Customer is the main entity):

  public class Customer {

  private final String id;

  private String contactName;

  private String phone;

  public void setId(String id) { this.id = id; }

  public String getId() { return this.id; }

  public void setContactName(String cn) { this.contactName = cn;}

  public String getContactName() { return this.contactName; }

  public void setPhone(String phone) { this.phone = phone; }

  public String getPhone() { return this.phone; }

  }

  public interface CustomerDAO {

  public void addCustomer(Customer c) throws DataAccessException;

  public Customer getCustomer(String id) throws DataAccessException;

  public List getCustomers() throws DataAccessException;

  public void removeCustomer(String id) throws DataAccessException;

  public void modifyCustomer(Customer c) throws DataAccessException;

  }

• Question 119:

  Given:

  import java.io.IOException;

  import java.io.file.Path;

  import java.io.file.Paths;

  public class Path12 {

  public static void main(String s[]) throws IOException {

  Path path = Paths.get("\\sales\\quarter\\..\\qtrlreport.txt");

  path.relativize(Paths.get("\\sales\\annualreport.txt"));

  if(path.endsWith("annualreport.txt")) {

  System.out.println(true);

  } else {

  System.out.println(false);

  }

  System.out.println(path);

  }

  }

  What is the result?

  A. false \sales\quarter\ . . \qtrlreport.txt
  B. false \quarter\ . . \qtrlreport.txt
  C. true . . \ . . \ . . \ annualreport.txt
  D. true \ . . \ . . \annualreport.txt
  A. false \sales\quarter\ . . \qtrlreport.txt

  ---

  The relativize method that can be used to construct a relative path between two paths.

  relativize

  Path relativize(Path other)

  Constructs a relative path between this path and a given path.

  Parameters:

  other - the path to relativize against this path

  Returns:

  the resulting relative path, or an empty path if both paths are equal

  Note:

  Relativization is the inverse of resolution. This method attempts to construct a relative path that when resolved against this path, yields a path that locates the same file as the given path. For example, on UNIX, if this path is "/a/b" and the

  given path is "/a/b/c/d" then the resulting relative path would be "c/d". Where this path and the given path do not have a root component, then a relative path can be constructed. A relative path cannot be constructed if only one of the paths

  have a root component. Where both paths have a root component then it is implementation dependent if a relative path can be constructed. If this path and the given path are equal then an empty path is returned.

  For any two normalized paths p and q, where q does not have a root component,

  p.relativize(p.resolve(q)).equals(q)

  When symbolic links are supported, then whether the resulting path, when resolved against this path, yields a path that can be used to locate the same file as other is implementation

  dependent. For example, if this path is "/a/b" and the given path is "/a/x" then the resulting relative path may be "../x". If "b" is a symbolic link then is implementation dependent if "a/b/../x" would locate the same file as "/a/x".

• Question 120:

  Given the code fragment:

  

  If the file userguide.txt does not exist, what is the result?

  A. An empty file is created and success is printed.
  B. class java.io.FileNotFoundException.
  C. class java.io.IOException.
  D. class java.lang.Exception.
  E. Compilation fails.
  B. class java.io.FileNotFoundException.

  ---

  Note: public FileReader(String fileName) throws FileNotFoundException Creates a new FileReader, given the name of the file to read from.

  Parameters:

  fileName - the name of the file to read from

  Throws:

  FileNotFoundException - if the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading. Reference: java.io Class FileReader