March 29, 2026 • 2 min read

Weekly Engineering Mastery Quiz (2026-03-23 to 2026-03-27)

A 20-question assessment covering fundamentals, implementation best practices, and advanced architecture insights from this week’s learning posts.

#Learning-log#Quiz#Assessment Weekly Quiz

Table of contents

Interactive Quiz

Weekly engineering recap (Europe/London) Coverage: 2026-03-23 → 2026-03-27 • Run date: 2026-03-29

Focus: Kotlin — Variables & Types (Fundamental refresher)

Key takeaways

val vs var: val is a read‑only reference (single assignment); var is reassignable. Object mutability is independent of reference mutability.
Type inference: The compiler infers types from initializers. For integer literals, inference starts at Int and widens to Long when needed; floating literals default to Double.
Basic types: Numbers (Byte/Short/Int/Long, U* variants, Float/Double), Boolean, Char, and String behave like classes with operators and utilities; there are no implicit numeric widenings.
String templates: Use $name and ${expr}. Triple‑quoted strings (""") support raw text; use ${’$’} for a literal dollar. New multi‑dollar interpolation (experimental) lets you require multiple $ to trigger interpolation.
Any, Unit, Nothing: Any is the root of all non‑null types; Unit is a single‑value return type for “no meaningful value”; Nothing is the bottom type (expressions that never return, e.g., throw or error).
Practical tips: Prefer val by default; add explicit types when inference is unclear (e.g., empty collections); avoid referential equality (===) for boxed numbers on the JVM; use == for value equality.
2026 notes: IDEs use the K2 compiler frontend by default in Kotlin 2.x; expect clearer diagnostics and some stricter checks. Review plugin compatibility and migration notes. Multi‑dollar string interpolation is available as an experimental feature.

Interactive Quiz

Use the interactive quiz section below to answer each question and get instant feedback.

Interactive Quiz

Score: 0 / 20 | Answered: 0 / 20

Q1 In Kotlin, which statement about val is correct?

Fundamentals

A. val can be reassigned after initialization. B. A val reference can’t be reassigned, though the referenced object may be mutable. C. val variables must declare an explicit type. D. val values are computed only at compile time.

Select one option.

Q2 Which best describes Kotlin’s type inference?

Fundamentals

A. You must always annotate types. B. Numeric literals default to Double regardless of context. C. The compiler infers from initializers; integers start at Int and widen to Long if needed. D. Inferred types can change at runtime.

Select one option.

Q3 Which declaration is inferred as Long by the compiler?

Fundamentals

A. val x = 3000000000 B. val x = 1.0 C. val x = 1F D. val x = 42

Select one option.

Q4 Which string correctly embeds s.length using templates?

Fundamentals

A. "Length: $s.length" B. "Length: $(s.length)" C. "Length: ${s.length}" D. "Length: ${{s}.length}"

Select one option.

Q5 Which of the following snippets compile? (Assume they’re in the same scope.)

Fundamentals

A. val x: Int; x = 10; println(x) B. var y: String = null C. val z = mutableListOf(1); z.add(2) D. val w: Double = 1

Select one or more options.

Q6 What does val list = mutableListOf(1) guarantee?

Intermediate

A. list.add is not allowed. B. The list’s contents are immutable. C. list can be reassigned to a new list. D. The reference is stable, but the list can mutate.

Select one option.

Q7 Given fun f(x: Double), which call compiles without conversion?

Intermediate

A. f(1) B. f(1.0) C. val x = 1f; f(x) D. val y: Long = 1; f(y)

Select one option.

Q8 Which boolean expression evaluates to true?

Intermediate

A. true && !false B. false || (false && true) C. !(true || true) D. true && (false || false)

Select one option.

Q9 Which literal is a Char?

Intermediate

A. "A" B. 'AB' C. 'A' D. 65

Select one option.

Q10 In a triple‑quoted string, which snippets ensure a literal $ appears (not interpolation)?

Intermediate

A. """ Total: ${'$'}amount """ B. $$""" Total: $price """ C. """ Total: $amount """ D. """ Total: $${amount} """

Select one or more options.

Q11 Which statement about Any, Unit, and Nothing is correct?

Intermediate

A. Any is the root of all non‑null Kotlin types. B. Unit has many distinct values. C. Nothing is the supertype of all types. D. Any includes null.

Select one option.

Q12 Which statements about Kotlin’s type inference are true?

Intermediate

A. You can omit types when the initializer makes the type obvious. B. Empty collections often need explicit type arguments. C. Inferred types can change after code runs. D. Floating literals default to Float.

Select one or more options.

Q13 Which function signature indicates the function never returns normally?

Advanced

A. fun fail(): Unit B. fun fail(): Any C. fun fail(): Nothing? D. fun fail(): Nothing

Select one option.

Q14 Which property override is allowed in Kotlin?

Advanced

A. Override val with val when the base is var. B. Override val with var when the base is val (with open/override). C. You may only override val with val. D. Override rules ignore val/var differences.

Select one option.

Q15 Which statement about const val is correct?

Advanced

A. It can be used for local variables. B. It may be declared with var. C. It must be top‑level or in an object/companion and be a primitive or String. D. It can hold any reference type.

Select one option.

Q16 K2 compiler migration facts (select all that apply):

Advanced

A. K2 is the new compiler frontend enabled with Kotlin 2.x. B. Some diagnostics and inference differ; small code fixes may be needed. C. K2 removes string templates from the language. D. You should verify compiler plugin compatibility with K2.

Select one or more options.

Q17 What is the type of println("hi")?

Advanced

A. Unit B. Nothing C. Any D. String

Select one option.

Q18 On the JVM, which statement about numbers and referential equality (===) is correct?

Advanced

A. All boxed Int? values are cached, so === is safe. B. Two boxed Int? values of 1000 are === equal. C. Use === for numeric comparisons. D. Small boxed numbers may be cached; prefer == for value equality.

Select one option.

Q19 Which uses of Nothing enable type‑checking?

Advanced

A. val s: String = (name ?: error("missing")) B. val n: Int = if (ok) 1 else throw IllegalStateException() C. fun f(): Int = throw RuntimeException() D. val x: Nothing = 42

Select one or more options.

Q20 Which statement about Any and Any? is correct?

Advanced

A. Any is nullable and can hold null. B. Any? can hold null. C. Any has all members of every type. D. Any is defined as an interface.

Select one option.

References

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