Kotlin Part-II

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Kotlin Part-II

Your function is passed by a parameter obj of type Any. Which code snippet shows a way to retrieve the original type of obj, including package information? *

1 point

obj.classInfo()

obj.typeInfo()

obj::class.simpleName

obj::class

Both const and @JvmField create constants. What can const do that @JvmField cannot? *

1 point

const is compatible with Java, but @JvmField is not

The compiler will inline const so it is faster and more memory efficient

Virtually any type can be used with const but not @JvmField

const can also be used with mutable types

Which is the correct declaration of an integer array with a size of 5? *

1 point

val arrs[5]: Int

val arrs = IntArray(5)

val arrs: Int[5]

val arrs = Array<Int>(5)

You have an enum class Signal that represents the state of a network connection. You want to print the position number of the SENDING enum. Which line of code does that? *

1 point

println(Signal.SENDING.position())

println(Signal.SENDING.hashCode())

println(Signal.SENDING)

println(Signal.SENDING.ordinal)

Which line of code is a shorter, more idiomatic version of the displayed snippet? *

1 point

val len = x?.let{x.len} else {-1}

val len = x!!.length ?: -1

val len:Int = (x != null)? x.length : -1

val len = x?.length ?: -1

The code below is expected to display the numbers from 1 to 10, but it does not. Why? *

1 point

You cannot assign a sequence to a variable

To produce result, a sequence must have terminal operation. In this case, it needs a .toList()

The .filter{ it < 11 } should be .filter{ it > 11 }

The yieldAll(1..20) should be yieldAll(1..10)

Which snippet correctly shows setting the variable max to whichever variable holds the greatest value, a or b, using idiomatic Kotlin? *

1 point

val max3 = a.max(b) (Extension Function is One of the idiomatic Solutions in Kotlin)

val max = a > b ? a : b

val max = if (a > b) a else b

if (a > b) max = a else max = b

What is the correct way to initialize a nullable variable? *

1 point

val name = null

var name: String

val name: String

val name: String? = null

This function generates Fibonacci sequence. Which function is missing? *

1 point

with()

yield()

skip()

return()

In this code snippet, why does the compiler not allow the value of y to change? *

1 point

y must be declared with var to be mutable

y is an implicitly immutable value

y can change only in a while loop

In order to change y, it must be declared outside of the loop

The code snippet below translates a database user to a model user. Because their names are both User, you must use their fully qualified names, which is cumbersome. You do not have access to either of the imported classes' source code. How can you shorten the type names? *

1 point

Use import as to change the type name

Create subtypes with shorter names

Create interfaces with shorter names

Create extension classes with shorter names

How can you retrieve the value of the property codeName without referring to it by name or destructuring? *

1 point

proj.0

proj[0]

proj[1]

proj.component1()

Kotlin has two equality operators, == and ===. What is the difference? *

1 point

== determines if two primitive types are identical. === determines if two objects are identical

== determines if two references point to the same object. === determines if two objects have the same value

== determines if two objects have the same value. === determines if two strings have the same value

== determines if two objects have the same value. === determines if two references point to the same object

What is the difference between the declarations of COLOR and SIZE? *

1 point

Since COLOR and SIZE are both immutable, they are identical internally

Both are immutable, but the use of the keyword const makes COLOR slower and less space efficient than SIZE

const makes COLOR faster, but not compatible with Java. Without const, SIZE is still compatible with Java

Both are immutable, but the use of the keyword const makes COLOR faster and more space efficient than SIZE

In order to subclass the Person class, what is one thing you must do? *

1 point

The subclass must be marked sealed

You must override the displayJob() method

You must mark the subclass as final

An abstract class cannot be extended, so you must change it to open

Why doesn't this code compile? *

1 point

infix function must be marked public

In Kotlin, add is a keyword

Extension functions use it, not this, as the default parameter name

infix functions cannot have default values

Which is the proper way to declare a singleton named DatabaseManager? *

1 point

object DatabaseManager {}

singleton DatabaseManager {}

static class DatabaseManager {}

data class DatabaseManager {}

Why does not this code snippet compile? *

1 point

Because name is a class parameter, not a property-it is unresolved main().

In order to create an instance of a class, you need the keyword new

The reference to name needs to be scoped to the class, so it should be this.name

Classes cannot be immutable. You need to change var to val

What three methods does this class have? *

1 point

equals(), hashCode(), and toString()

equals(), toHash(), and super()

print(), println(), and toString()

clone(), equals(), and super()

You would like to know each time a class property is updated. Which code snippet shows a built-in delegated property that can accomplish this? *

1 point

Delegates.watcher()

Delegates.observable()

Delegates.rx()

Delegates.observer()

You have a when expression for all of the subclasses of the class Attribute. To satisfy the when, you must include an else clause. Unfortunately, whenever a new subclass is added, it returns unknown. You would prefer to remove the else clause so the compiler generates an error for unknown subtypes. What is one simple thing you can do to achieve this? *

1 point

Replace open with closed

Replace open with sealed

Replace open with private

Replace open with public

You are creating a Kotlin unit test library. What else should you add to make the following code compile without error? *

1 point

The extension function should be marked public

Add the prefix operator to the shouldMatch extension function

The code is not legal in Kotlin (should be println(msg.shouldEqual("test message")))

Add the prefix infix to the shouldMatch extension function

The code below shows a typical way to show both index and value in many languages, including Kotlin. Which line of code shows a way to get both index and value more idiomatically? *

1 point