oracle 1Z0-809 Exam Questions

Questions for the 1Z0-809 were updated on : Jun 07 ,2024

Page 1 out of 11. Viewing questions 1-15 out of 164

Question 1

Given the definition of the Vehicle class:
Class Vehhicle {
int distance;//line n1
Vehicle (int x) {
this distance = x;
}
public void increSpeed(int time) {//line n2
int timeTravel = time;//line n3
class Car {
int value = 0;
public void speed () {
value = distance /timeTravel;
System.out.println (Velocity with new speed+value+kmph);
}
}
new Car().speed();
}
}
and this code fragment:
Vehicle v = new Vehicle (100);
v.increSpeed(60);
What is the result?

  • A. Velocity with new speed
  • B. A compilation error occurs at line n1.
  • C. A compilation error occurs at line n2.
  • D. A compilation error occurs at line n3.
Answer:

A

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Question 2

Given:
IntStream stream = IntStream.of (1,2,3);
IntFunction<Integer> inFu= x -> y -> x*y;//line n1
IntStream newStream = stream.map(inFu.apply(10));//line n2
newStream.forEach(System.out::print);
Which modification enables the code fragment to compile?

  • A. Replace line n1 with:IntFunction<UnaryOperator> inFu = x -> y -> x*y;
  • B. Replace line n1 with:IntFunction<IntUnaryOperator> inFu = x -> y -> x*y;
  • C. Replace line n1 with:BiFunction<IntUnaryOperator> inFu = x -> y -> x*y;
  • D. Replace line n2 with:IntStream newStream = stream.map(inFu.applyAsInt (10));
Answer:

B

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Question 3

Given the code fragment:
List<Integer> values = Arrays.asList (1, 2, 3);
values.stream ()
.map(n -> n*2)//line n1
.peek(System.out::print)//line n2
.count();
What is the result?

  • A. 246
  • B. The code produces no output.
  • C. A compilation error occurs at line n1.
  • D. A compilation error occurs at line n2.
Answer:

A

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Question 4

Given the code fragment:
public class Foo {
public static void main (String [ ] args) {
Map<Integer, String> unsortMap = new HashMap< > ( );
unsortMap.put (10, z);
unsortMap.put (5, b);
unsortMap.put (1, d);
unsortMap.put (7, e);
unsortMap.put (50, j);
Map<Integer, String> treeMap = new TreeMap <Integer, String> (new
Comparator<Integer> ( ) {
@Override public int compare (Integer o1, Integer o2) {return o2.compareTo
(o1); } } );
treeMap.putAll (unsortMap);
for (Map.Entry<Integer, String> entry : treeMap.entrySet () ) {
System.out.print (entry.getValue () + );
}
}
}
What is the result?

  • A. A compilation error occurs.
  • B. d b e z j
  • C. j z e b d
  • D. z b d e j
Answer:

C

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Question 5

Which two reasons should you use interfaces instead of abstract classes? (Choose two.)

  • A. You expect that classes that implement your interfaces have many common methods or fields, or require access modifiers other than public.
  • B. You expect that unrelated classes would implement your interfaces.
  • C. You want to share code among several closely related classes.
  • D. You want to declare non-static on non-final fields.
  • E. You want to take advantage of multiple inheritance of type.
Answer:

B,E

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Question 6

Given:
public class Counter {
public static void main (String[ ] args) {
int a = 10;
int b = -1;
assert (b >=1) : Invalid Denominator;
int = a / b;
System.out.println (c);
}
}
What is the result of running the code with the ea option?

  • A. -10
  • B. 0
  • C. An AssertionError is thrown.
  • D. A compilation error occurs.
Answer:

C

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Question 7

Given:
class Bird {
public void fly () { System.out.print(Can fly); }
}
class Penguin extends Bird {
public void fly () { System.out.print(Cannot fly); }
}
and the code fragment:
class Birdie {
public static void main (String [ ] args) {
fly( ( ) -> new Bird ( ));
fly (Penguin : : new);
}
/* line n1 */
}
Which code fragment, when inserted at line n1, enables the Birdie class to compile?

  • A. static void fly (Consumer<Bird> bird) {bird :: fly ();}
  • B. static void fly (Consumer<? extends Bird> bird) {bird.accept( ) fly ();}
  • C. static void fly (Supplier<Bird> bird) {bird.get( ) fly ();}
  • D. static void fly (Supplier<? extends Bird> bird) {LOST
Answer:

C

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Question 8

Given:
1. abstract class Shape {
2. Shape ( ) { System.out.println (Shape); }
3. protected void area ( ) { System.out.println (Shape); }
4. }
5.
6. class Square extends Shape {
7. int side;
8. Square int side {
9./* insert code here */
10. this.side = side;
11. }
12. public void area ( ) { System.out.println (Square); }
13. }
14. class Rectangle extends Square {
15. int len, br;
16. Rectangle (int x, int y) {
17. /* insert code here */
18. len = x, br = y;
19. }
20. void area ( ) { System.out.println (Rectangle); }
21. }
Which two modifications enable the code to compile? (Choose two.)

  • A. At line 1, remove abstract
  • B. At line 9, insert super ( );
  • C. At line 12, remove public
  • D. At line 17, insert super (x);
  • E. At line 17, insert super (); super.side = x;
  • F. At line 20, use public void area ( ) {
Answer:

D,F

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Question 9

Given:
class Sum extends RecursiveAction { //line n1
static final int THRESHOLD_SIZE = 3;
int stIndex, lstIndex;
int [ ] data;
public Sum (int [ ]data, int start, int end) {
this.data = data;
this stIndex = start;
this. lstIndex = end;
}
protected void compute ( ) {
int sum = 0;
if (lstIndex stIndex <= THRESHOLD_SIZE) {
for (int i = stIndex; i < lstIndex; i++) {
sum += data [i];
}
System.out.println(sum);
} else {
new Sum (data, stIndex + THRESHOLD_SIZE, lstIndex).fork( );
new Sum (data, stIndex,
Math.min (lstIndex, stIndex + THRESHOLD_SIZE)
).compute ();
}
}
}
and the code fragment:
ForkJoinPool fjPool = new ForkJoinPool ( );
int data [ ] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
fjPool.invoke (new Sum (data, 0, data.length));
and given that the sum of all integers from 1 to 10 is 55.
Which statement is true?

  • A. The program prints several values that total 55.
  • B. The program prints 55.
  • C. A compilation error occurs at line n1.
  • D. The program prints several values whose sum exceeds 55.
Answer:

C

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Question 10

Given the content of Operator.java, EngineOperator.java, and Engine.java files:

and the code fragment:

What is the result?

  • A. The Engine.java file fails to compile.
  • B. The EngineOperator.java file fails to compile.
  • C. The Operator.java file fails to compile.
  • D. ON OFF
Answer:

A

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Question 11

Given the code fragment:
Stream<List<String>> iStr= Stream.of (
Arrays.asList (1, John),
Arrays.asList (2, null)0;
Stream<<String> nInSt = iStr.flatMapToInt ((x) -> x.stream ());
nInSt.forEach (System.out :: print);
What is the result?

  • A. 1John2null
  • B. 12
  • C. A NullPointerException is thrown at run time.
  • D. A compilation error occurs.
Answer:

D

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Question 12

Given the code fragment:
Path file = Paths.get (courses.txt);
// line n1
Assume the courses.txt is accessible.
Which code fragment can be inserted at line n1 to enable the code to print the content of the
courses.txt file?

  • A. List<String> fc = Files.list(file);fc.stream().forEach (s - > System.out.println(s));
  • B. Stream<String> fc = Files.readAllLines (file);fc.forEach (s - > System.out.println(s));
  • C. List<String> fc = readAllLines(file);fc.stream().forEach (s - > System.out.println(s));
  • D. Stream<String> fc = Files.lines (file);fc.forEach (s - > System.out.println(s));
Answer:

D

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Question 13

Given the code fragment:
public void recDelete (String dirName) throws IOException {
File [ ] listOfFiles = new File (dirName) .listFiles();
if (listOfFiles ! = null && listOfFiles.length >0) {
for (File aFile : listOfFiles) {
if (aFile.isDirectory ()) {
recDelete (aFile.getAbsolutePath ());
} else {
if (aFile.getName ().endsWith (.class))
aFile.delete ();
}
}
}
}
Assume that Projects contains subdirectories that contain .class files and is passed as an argument to
the recDelete () method when it is invoked.
What is the result?

  • A. The method deletes all the .class files in the Projects directory and its subdirectories.
  • B. The method deletes the .class files of the Projects directory only.
  • C. The method executes and does not make any changes to the Projects directory.
  • D. The method throws an IOException.
Answer:

A

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Question 14

Given the code fragments:
4. void doStuff() throws ArithmeticException, NumberFormatException, Exception {
5. if (Math.random() >-1 throw new Exception (Try again);
6. }
and
24. try {
25. doStuff ( ):
26. } catch (ArithmeticException | NumberFormatException | Exception e) {
27. System.out.println (e.getMessage()); }
28. catch (Exception e) {
29. System.out.println (e.getMessage()); }
30. }
Which modification enables the code to print Try again?

  • A. Comment the lines 28, 29 and 30.
  • B. Replace line 26 with:} catch (Exception | ArithmeticException | NumberFormatException e) {
  • C. Replace line 26 with:} catch (ArithmeticException | NumberFormatException e) {
  • D. Replace line 27 with:throw e;
Answer:

C

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Question 15

Given the definition of the Country class:
public class country {
public enum Continent {ASIA, EUROPE}
String name;
Continent region;
public Country (String na, Continent reg) {
name = na, region = reg;
}
public String getName () {return name;}
public Continent getRegion () {return region;}
}
and the code fragment:
List<Country> couList = Arrays.asList (
new Country (Japan, Country.Continent.ASIA),
new Country (Italy, Country.Continent.EUROPE),
new Country (Germany, Country.Continent.EUROPE));
Map<Country.Continent, List<String>> regionNames = couList.stream ()
.collect(Collectors.groupingBy (Country ::getRegion,
Collectors.mapping(Country::getName, Collectors.toList()))));
System.out.println(regionNames);
What is the output?

  • A. {EUROPE = [Italy, Germany], ASIA = [Japan]}
  • B. {ASIA = [Japan], EUROPE = [Italy, Germany]}
  • C. {EUROPE = [Germany, Italy], ASIA = [Japan]}
  • D. {EUROPE = [Germany], EUROPE = [Italy], ASIA = [Japan]}
Answer:

B

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