Oracle Oracle Certifications 1Z0-808 Questions & Answers

• Question 251:

  Given:

  

  How many objects have been created when the line / / do complex stuff is reached?

  A. Two

  B. Three

  C. Four

  D. Six

  Correct Answer: C

• Question 252:

  Given: What is the result?

  

  A. int main 1

  B. Object main 1

  C. String main 1

  D. Compilation fails

  E. An exception is thrown at runtime

  Correct Answer: C

• Question 253:

  Which three statements are benefits of encapsulation?

  A. Allows a class implementation to change without changing t he clients

  B. Protects confidential data from leaking out of the objects

  C. Prevents code from causing exceptions

  D. Enables the class implementation to protect its invariants

  E. Permits classes to be combined into the same package

  F. Enables multiple instances of the same class to be created safely

  Correct Answer: ABD

• Question 254:

  Given the code in a file Traveler.java:

  

  And the commands: Javac Traveler.java Java Traveler Java Duke What is the result?

  A. Happy Journey! Duke

  B. Happy Journey! Java

  C. An exception is thrown at runtime

  D. The program fails to execute due to a runtime error

  Correct Answer: D

• Question 255:

  Given:

  

  How many MarkList instances are created in memory at runtime?

  A. 1

  B. 2

  C. 3

  D. 4

  Correct Answer: A

• Question 256:

  Given:

  

  What is the result?

  A. The sum is 2

  B. The sum is 14

  C. The sum is 15

  D. The loop executes infinite times

  E. Compilation fails

  Correct Answer: E

• Question 257:

  Given:

  public class X {

  static int i;

  int j;

  public static void main(String[] args) {

  X x1 = new X();

  X x2 = new X();

  x1.i = 3;

  x1.j = 4;

  x2.i = 5;

  x2.j = 6;

  System.out.println(

  x1.i + " "+

  x1.j + " "+

  x2.i + " "+

  x2.j);

  }

  }

  What is the result?

  A. 3 4 5 6

  B. 3 4 3 6

  C. 5 4 5 6

  D. 3 6 4 6

  Correct Answer: C

• Question 258:

  Given: A. true, false

  

  B. false, true

  C. true, true

  D. false, false

  Correct Answer: A

  Explanation: == strict equality. equals compare state, not identity.

• Question 259:

  Given: Which constructor initializes the variable x3?

  

  A. Only the default constructor of class X

  B. Only the no-argument constructor of class Y

  C. Only the no-argument constructor of class Z

  D. Only the default constructor of object class

  Correct Answer: C

• Question 260:

  Given the classes:

  *

  AssertionError

  *

  ArithmeticException

  *

  ArrayIndexOutofBoundsException

  *

  FileNotFoundException

  *

  IllegalArgumentException

  *

  IOError

  *

  IOException

  *

  NumberFormatException

  *

  SQLException

  Which option lists only those classes that belong to the unchecked exception category?

  A. AssertionError, ArrayIndexOutOfBoundsException, ArithmeticException

  B. AssertionError, IOError, IOException

  C. ArithmeticException, FileNotFoundException, NumberFormatException

  D. FileNotFoundException, IOException, SQLException

  E. ArrayIndexOutOfBoundException, IllegalArgumentException, FileNotFoundException

  Correct Answer: A

  Explanation: Not B: IOError and IOException are both checked errors. Not C, not D, not E:

  FileNotFoundException is a checked error.

  Note:

  Checked exceptions:

  *

  represent invalid conditions in areas outside the immediate control of the program (invalid user input, database problems, network outages, absent files)

  *

  are subclasses of Exception

  *

  a method is obliged to establish a policy for all checked exceptions thrown by its implementation (either pass the checked exception further up the stack, or handle it somehow)

  Note:

  Unchecked exceptions:

  *

  represent defects in the program (bugs) - often invalid arguments passed to a non-private method. To

  quote from The Java Programming Language, by Gosling, Arnold, and Holmes:

  "Unchecked runtime exceptions represent conditions that, generally speaking, reflect errors in your

  program's logic and cannot be reasonably recovered from at run time."

  *

  are subclasses of RuntimeException, and are usually implemented using IllegalArgumentException,

  NullPointerException, or IllegalStateException

  *

  method is not obliged to establish a policy for the unchecked exceptions thrown by its implementation

  (and they almost always do not do so)