Oracle Java SE 1Z0-819 Questions & Answers

• Question 11:

  Given:

  

  and

  

  What is the result?

  A. A NullPointerException is thrown at run time.

  B. The compilation fails.

  C. 1 Null null

  D. 1

  E. A ClassCastException is thrown at run time.

  Correct Answer: B

  

• Question 12:

  Given:

  

  and checkQuality(QUALITY.A); and Which code fragment can be inserted into the switch statement to print Best?

  

  A. QUALITY.A.ValueOf()

  B. A

  C. A.toString()

  D. QUALITY.A

  Correct Answer: B

• Question 13:

  Given:

  

  Which statement on line 1 enables this code fragment to compile?

  A. Function function = String::toUpperCase;

  B. UnaryOperator function = s > s.toUpperCase();

  C. UnaryOperator function = String::toUpperCase;

  D. Function function = m > m.toUpperCase();

  Correct Answer: C

  

• Question 14:

  Why would you choose to use a peek operation instead of a forEach operation on a Stream?

  A. to process the current item and return void

  B. to remove an item from the end of the stream

  C. to process the current item and return a stream

  D. to remove an item from the beginning of the stream

  Correct Answer: C

  Reference: https://www.baeldung.com/java-streams-peek-api

• Question 15:

  Given: /code/a/Test.java containing:

  

  and

  /code/b/Best.java

  containing:

  package b;

  public class Best { }

  Which is the valid way to generate bytecode for all classes?

  A. java /code/a/Test.java

  B. javac -d /code /code/a/Test

  C. java /code/a/Test.java /code/b/Best.java

  D. java -cp /code a.Test

  E. javac -d /code /code/a/Test.java /code/b/Best.java

  F. javac -d /code /code/a/Test.java

  Correct Answer: E

• Question 16:

  Given:

  

  Which statement is equivalent to line 1?

  A. double totalSalary = list.stream().map(e > e.getSalary() * ratio).reduce (bo).ifPresent (p > p.doubleValue());

  B. double totalSalary = list.stream().mapToDouble(e > e.getSalary() * ratio).sum;

  C. double totalSalary = list.stream().map(Employee::getSalary * ratio).reduce (bo).orElse(0.0);

  D. double totalSalary = list.stream().mapToDouble(e > e.getSalary() * ratio).reduce(starts, bo);

  Correct Answer: C

  

• Question 17:

  Examine this excerpt from the declaration of the java.se module: What does the transitive modifier mean?

  

  A. Only a module that requires the java.se module is permitted to require the java.sql module.

  B. Any module that requires the java.se module does not need to require the java.sql module.

  C. Any module that attempts to require the java.se module actually requires the java.sql module instead.

  D. Any module that requires the java.sql module does not need to require the java.se module.

  Correct Answer: A

• Question 18:

  Given:

  

  and the code fragment:

  Which two Map objects group all employees with a salary greater than 30 by neighborhood? (Choose two.)

  

  A. Option A

  B. Option B

  C. Option C

  D. Option D

  E. Option E

  Correct Answer: A

• Question 19:

  Given:

  

  Which would cause s to be AQCD?

  A. s.replace(s.indexOf("A"), s.indexOf("C"), "Q");

  B. s.replace(s.indexOf("B"), s.indexOf("C"), "Q");

  C. s.replace(s.indexOf("B"), s.indexOf("B"), "Q");

  D. s.replace(s.indexOf("A"), s.indexOf("B"), "Q");

  Correct Answer: B

• Question 20:

  Given:

  

  Assuming that this code compiles correctly, which three statements are true? (Choose three.)

  A. A cannot be abstract.

  B. A cannot be final.

  C. B cannot be abstract.

  D. B cannot be final.

  E. B is a subtype of A.

  F. A is A is a subtype of B.a subtype of B.

  Correct Answer: BCE

  The correct answers are B. A cannot be final, C. B cannot be abstract, and E. B is a subtype of A.

  Since the code compiles correctly, the method build in the BuilderImpl class must be a valid implementation of the method declared in the Question70 interface. This means that the return type of the build method in the BuilderImpl class, which is B, must be a subtype of the return type of the build method in the Builder interface, which is A. Therefore, option E is correct.