1Z0-811 Core Java API 4

Question 1

Which method in `Iterable` is used to perform an action for each element?

Accepted Answer

forEach()

Answer

`Iterable.forEach(Consumer)` iterates over all elements and applies the given action to each.

Question 2

What is the result of `new StringBuilder("abc").insert(1, "XY")`?

Accepted Answer

"aXYbc"

Answer

`insert(1, "XY")` inserts "XY" starting at index 1, shifting existing characters right, resulting in "aXYbc".

Question 3

Which of these correctly declares a `Set` that preserves insertion order?

Accepted Answer

new LinkedHashSet<>()

Answer

`LinkedHashSet` maintains insertion order using a doubly-linked list alongside the hash table.

Question 4

What does `LocalDate.now().plusMonths(1).getMonth()` return if today is January 31?

Accepted Answer

February

Answer

Adding one month to January 31 yields February 28 (or 29 in a leap year); the month is February.

Question 5

What is the output of `System.out.println("  hello  ".strip())`?

Accepted Answer

"hello"

Answer

`String.strip()` removes leading and trailing whitespace (including Unicode whitespace), returning "hello".

(1Z0-811) Oracle Java SE11 Programmer Practice Test