Oracle Java SE 21 Developer Professional Sample Questions:

1. Given:
java
Runnable task1 = () -> System.out.println("Executing Task-1");
Callable<String> task2 = () -> {
System.out.println("Executing Task-2");
return "Task-2 Finish.";
};
ExecutorService execService = Executors.newCachedThreadPool();
// INSERT CODE HERE
execService.awaitTermination(3, TimeUnit.SECONDS);
execService.shutdownNow();
Which of the following statements, inserted in the code above, printsboth:
"Executing Task-2" and "Executing Task-1"?

A) execService.submit(task1);
B) execService.call(task1);
C) execService.run(task1);
D) execService.execute(task1);
E) execService.run(task2);
F) execService.submit(task2);
G) execService.execute(task2);
H) execService.call(task2);

2. Given:
java
var frenchCities = new TreeSet<String>();
frenchCities.add("Paris");
frenchCities.add("Marseille");
frenchCities.add("Lyon");
frenchCities.add("Lille");
frenchCities.add("Toulouse");
System.out.println(frenchCities.headSet("Marseille"));
What will be printed?

A) [Paris]
B) Compilation fails
C) [Lyon, Lille, Toulouse]
D) [Paris, Toulouse]
E) [Lille, Lyon]

3. Which of the following doesnotexist?

A) BiSupplier<T, U, R>
B) Supplier<T>
C) They all exist.
D) LongSupplier
E) BooleanSupplier
F) DoubleSupplier

4. Given:
java
var now = LocalDate.now();
var format1 = new DateTimeFormatter(ISO_WEEK_DATE);
var format2 = DateTimeFormatter.ISO_WEEK_DATE;
var format3 = new DateFormat(WEEK_OF_YEAR_FIELD);
var format4 = DateFormat.getDateInstance(WEEK_OF_YEAR_FIELD);
System.out.println(now.format(REPLACE_HERE));
Which variable prints 2025-W01-2 (present-day is 12/31/2024)?

A) format1
B) format4
C) format2
D) format3

5. Given:
java
LocalDate localDate = LocalDate.of(2020, 8, 8);
Date date = java.sql.Date.valueOf(localDate);
DateFormat formatter = new SimpleDateFormat(/* pattern */);
String output = formatter.format(date);
System.out.println(output);
It's known that the given code prints out "August 08".
Which of the following should be inserted as the pattern?

A) MMM dd
B) MM dd
C) MM d
D) MMMM dd

Solutions: