Main

Question 1

How is called a porcess where a single abstract method can be implemented using anonymous function?

Answer 1

Single Abstract Method Conversion (SAM)

Question 2

What do you pass instead if an object implements SAM?

Answer 2

lambda

Question 3

val age = 45. Write a conditional to check if age is even

Answer 3

age % 2 == 0

Question 4

build a raw String named player

Answer 4

val player : String = “””
Michael
Jordan
“””

Question 5

If “”” raw String is used do you need to use an escape characters?

Answer 5

NO

Question 6

For what Raw Strings are useful?

Answer 6

Regex patterns

Question 7

What kotlin ability we can use to add a function to 3rd party library?

Answer 7

extensions

Question 8

What type indicates that the function will never coplete normally

Answer 8

Nothing.

val thing : Nothing = TODO()

Question 9

If we write a function but we do not want to return yet

how can we stop compiler complaining about the error?

Answer 9

By using TODO
fun age() : Int {
TODO()
}

Question 10

Why Unit in kotlin is useful?

Answer 10

It can be used in generics. For instance, ‹

Question 11

4 Kotlin language principles

Answer 11

1.Concise 2.Pragmatic 3.Safe 4.Interoperable

Question 12

What is idiomatic language code

Answer 12

It is a code which is specific for a language

Question 13

How do we call Kotlin’s ability to work with Java code?

Answer 13

Interoperablility - the ability of computer systems or software to exchange and make use of information

Question 14

How to define that member variable is read-only ?

Answer 14

var hasBeenHnadled = false
private set // Allow read-only

Question 15

@JsonClass(generateAdapter = true)
data class AppConfiguration(
    val version: Int,
    val diagnosisKeysPerSubmit: Int,
    val pollingIntervalMinutes: Long,
    val tokenLength: Int
)
Let's say we have data which should be read-only, like the example above. How can we achieve this?

Answer 15

by specifying variable’s set() to private in the reposisitory

var appConfiguration: AppConfiguration
    private set

Question 16

If we have a large number of elements would we use SparseArray over HashMap

Answer 16

NO. Because SparseArray is only efficient if a collection is small. Less than 1000 elements

Question 17

What should be used if we have maps of maps? HashMap or SparseArray?

Answer 17

SparseArray

Question 18

How are called those values for function parameters
fun foo(a: Int = 0, b: String = "") { ... }

Answer 18

default values

Question 19

How is called the usage of $variable in the String?

Answer 19

String interpolation

Question 20

how is called this code

is Foo -> …

Answer 20

Instance check

Question 21

how is called this operation
for ((k, v) in map) {
println(“$k -> $v”)
}

Answer 21

traversing a map or list of pairs

Question 22

How would you call the usage of this
for (i in 1..100) { … } // closed range: includes 100
for (i in 1 until 100) { … } // half-open range: does not include 100
for (x in 2..10 step 2) { … }
for (x in 10 downTo 1) { … }
if (x in 1..10) { … }

Answer 22

Using ranges

Question 23

Is that map
val map = mapOf(“a” to 1, “b” to 2, “c” to 3)
read-only map ?

Answer 23

yes