INTRODUCTION

SELF REVIEW: PRACTICE DEFINING LISTENERS IN ANDROID

1. In the Practice defining listeners in Android exercise, when you ran the code, what did the app show on its screen?

2. What was the result of clicking the button with text Save Data?

3. Choose the options with the correct lambda expression syntax implementation.

5. What are the benefits of using a function as an object? Check all that apply.

6. Which of these represents a syntactically valid function type?

7. A lambda expression is a simple way to define a function as what? 

8. You have a button variable referencing a button component. How do you listen to click events on that button?

KNOWLEDGE CHECK: LAMBDA EXPRESSIONS

1. Which of these are correct ways to instantiate a function type. Select all that apply.

2. Which of these is a syntactically valid function type?

3. Which of these is a correct lambda expression syntax?

4. Which of these would output ‘hello world’ when the function defined below is called?

fun execute(string: String, function: (String) -> String) { 
println(function(string))
}

5. Which listener interface provided by the Android framework is used to listen for button press events?

SELF REVIEW: THE REPEAT FUNCTION

1. While the code in The repeat function exercise uses a function to generate random numbers, which of the following is a valid output for the wheel spin attempts?

2. Which of the following is the correct function definition for the repeat function?

3. Which of the following constructs is the repeat function similar to? 

4. Which of these correctly describes a higher order function?

5. A function that lets you define a function as a parameter to be executed inside the function is a higher-order function.

KNOWLEDGE CHECK: HIGHER ORDER FUNCTIONS

1. What is a higher-order function?

2. Which of these is a correct way to call the function greet:

fun greet(name: String, function: (name: String) -> Unit) {
  function(name)
}
fun print(name: String) {
  println("Hello $name")
}

3. Which of the following constructs is the repeat function similar to? 

4.  What is the output of the following code?

val number = 2
var output = 1
repeat(3) { index ->
 output += (index * number)
}
println(output)

SELF REVIEW: PROCESS COLLECTIONS

1. What was the sales tax amount output (up to 2 decimal places) when you ran your exercise’s code?

2. What would be the sales tax output (up to 2 decimal places) if you change the month to August and the sales tax percentage to 7.5%?

3. Which of the following functions does not return a List when called on an instance of List?

4. Which of the following are the steps involved in collection processing? 

5. forEach is an excellent example of an extension function and of a higher-order function.       

6. After map takes a transformation lambda as an input, what occurs next?    

7. You would use filter when you are only interested in some elements of your collection.   

8. If you are only interested in some elements in your collection, which function would you use?      

9. If you want to process a Kotlin collection and return a modified collection, you could use Kotlin’s collection processing functions.       

KNOWLEDGE CHECK: COLLECTIONS PROCESSING

1. What is the output of the following code?

var sum = 0
val numberList = listOf(2, 8, 3, 11) 
numberList.forEach { number ->
 sum += number
}
println(sum)

2. What is the output of this code:

data class Car(
val color: String,
val amount: Int
)
val list = listOf(
 Car("Black", 43000),
 Car("Red", 30000),
 Car("White", 36000)
)
val output = list.map { 
 it.color
}
println(output)

3. What do you expect to get as the output of this code?

val list = listOf(1, 3, 4, 7)
val output = list.fold(3) { x, y ->
 x + y
}
println(output)

4. What output would you expect for this code?

val numberMap = mapOf(
 5 to 6,
 3 to 2,
 8 to 7,
 4 to 1
)
val output = numberMap.map { entry ->
 entry.value
}.filter { 
 it > 3
}.fold(0) { x, y ->
 x + y
}
println(output)

5. What is the output of the code below:

data class Car( 
val color: String, 
val amount: Int 
) 
val list = listOf( 
  Car("Black", 43000), 
  Car("Red", 30000), 
  Car("White", 36000) 
)  
val output = list.filter { car -> 
  car.amount > 35000 
} 
println(output)

MODULE QUIZ: FUNCTIONAL PROGRAMMING

1. Which of these are correct ways to instantiate a function type. Select all that apply.

2. Which of these is a correct usage of lambda expression for the given function definition?

fun execute(number: Int, function: (Int) -> String) {
 println(function(number))
}

3. Which of the these is a correct lambda expression syntax?

4. Which listener interface provided by the Android framework is used to listen for a button press event?

5. Which of these are higher-order functions? Select all that apply.

6. What is the output of this code?

val number = 3
var output = 2
repeat(5) { index ->
 output += (index * number)
}
println(output)

7. What is the output of the following code?

var sum = 0
val numberList = listOf(1, 4, 6, 7, 9) 
numberList.forEach { number ->
 sum += number
}
println(sum)

8. What is the output of this code:

data class Chocolate( 
 val flavor: String, 
 val price: Int 
) 
val list = listOf( 
 Chocolate("Dark", 7), 
 Chocolate("Milk", 4), 
 Chocolate("Coffee", 2) 
)
val output = list.map { 
 it.flavor 
} 
println(output)

9. What is the output of this code:

data class Chocolate( 
 val flavor: String, 
 val price: Int 
) 
val list = listOf( 
 Chocolate("Dark", 7), 
 Chocolate("Milk", 4), 
 Chocolate("Coffee", 2) 
)
val output = list.filter { 
 it.price > 3
} 
println(output)

10. What is the output of this code:

val list = listOf(9, 3, 1, 6) 
val output = list.fold(1) { x, y -> 
 x + y 
} 	
println(output)

CONCLUSION