Oracle 1Z0-813 Online Practice Questions and Exam Preparation

Oracle 1Z0-813 Online Questions & Answers

• Question 1:

  Given:

  

  and the code fragment:

  

  Which code fragment, when inserted at line n1, results in the following output?

  600.0

  

  A. Option A
  B. Option B
  C. Option C
  D. Option D
  D. Option D

• Question 2:

  Given the code fragment: What is the result?

  

  A. All files and directories under the home directory are listed along with their attributes.
  B. A compilation error occurs at line n1.
  C. The files in the home directory are listed along with their attributes.
  D. A compilation error occurs at line n2.
  A. All files and directories under the home directory are listed along with their attributes.

• Question 3:

  Given the code fragment:

  

  What is the result?

  A. invalid
  B. An exception is thrown at runtime.
  C. NULL
  D. Compilation fails.
  E. blank
  B. An exception is thrown at runtime.

  ---

  A java.lang.NullPointerException is through at line switch(str) {.

• Question 4:

  Given the code fragment:

  

  What is the result?

  A. Word: why what when
  B. Words: why Word: Why what Word: why what when
  C. Word: why Word: what Word: when
  D. Compilation fails.
  A. Word: why what when

• Question 5:

  Which statement is true about the single abstract method of the java.util.function.Function interface?

  A. It accepts an argument and produces a result of any data type.
  B. It accepts one argument and always produces a result of the same type as the argument.
  C. It accepts one argument and returns void.
  D. It accepts one argument and returns boolean.
  A. It accepts an argument and produces a result of any data type.

  ---

  It represents a function that accepts one argument and produces a result.

  Reference: https://docs.oracle.com/javase/8/docs/api/java/util/function/Function.html

• Question 6:

  Given:

  

  Which result is possible?

  A. Compilation fails.
  B. L1 L2 L3
  C. L2 L3
  D. L1 L3
  E. L3
  B. L1 L2 L3

  ---

  The Runnable interface should be implemented by any class whose instances are intended to be executed by a thread. The class must define a method of no arguments called run. This interface is designed to provide a common protocol for objects that wish to execute code while they are active.

  Reference: http://docs.oracle.com/javase/7/docs/api/java/lang/Runnable.html

• Question 7:

  Given the code fragment:

  

  Which should be inserted into the line n1 to print Average = 2.5?

  A. Stream str = Stream.of(1, 2, 3, 4);
  B. IntStream str = IntStream.of(1, 2, 3, 4);
  C. DoubleStream str = Stream.of(1.0, 2.0, 3.0, 4.0);
  D. IntStream str = Stream.of(1, 2, 3, 4)
  B. IntStream str = IntStream.of(1, 2, 3, 4);

  ---

  Use IntStream.

  Reference: https://docs.oracle.com/javase/8/docs/api/java/util/stream/IntStream.html

• Question 8:

  Which two states are valid for a watch key? (Choose two.)

  A. Does Not Exist
  B. Signalled
  C. Ready
  D. Not Runnable
  E. Runnable
  B. Signalled
  C. Ready

  ---

  A watch key has a state. When initially created the key is said to be ready. When an event is detected then the key is signalled and queued so that it can be retrieved by invoking the watch service's poll or take methods. Once signalled, a key remains in this state until its reset method is invoked to return the key to the ready state.

  Reference: https://docs.oracle.com/javase/7/docs/api/java/nio/file/WatchKey.html

• Question 9:

  Given:

  

  and the code fragment:

  

  What is the result?

  A. A compilation error occurs.
  B. 2000.0
  C. 1500.0
  D. 0.0
  A. A compilation error occurs.

  ---

  The line mapToInt(Person::GetSalary) will cause a compile error.

  If it is replaced by the following line, a "." is added in the beginning of the line, the result would be 1500.0:

  .mapToInt(Person::getSalary)

• Question 10:

  Given the definitions of Readable and Writable interfaces:

  

  Given:

  

  What is the result?

  A. Compilation fails due to an error at line n3.
  B. Compilation fails due to an error at line n1.
  C. Hello Welcome Close
  D. Compilation fails due to an error at line n2.
  A. Compilation fails due to an error at line n3.

  ---

  Uncompilable source code - Uncompilable source code - Erroneous sym type: Writable.close at Writable.close(); // line n3.