Why interfaces are used in Go - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an interface named Speaker.

Go

type Speaker interface { [1]() string }

Drag options to blanks, or click blank then click option'

ASpeak

BRun

CWalk

DJump

Attempts:

3 left

💡 Hint

Common Mistakes

Using unrelated method names like Run or Walk in the Speaker interface.

The interface method name should be Speak to define a Speaker interface.

2fill in blank

medium

Complete the code to implement the Speaker interface for type Person.

Go

func (p Person) [1]() string { return "Hello" }

Drag options to blanks, or click blank then click option'

ARun

BJump

CSpeak

DWalk

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different method name that does not match the interface.

The method Speak matches the interface method and implements Speaker.

3fill in blank

hard

Fix the error in the code to assign a Person to a Speaker variable.

Go

var s Speaker = [1]

Drag options to blanks, or click blank then click option'

Aint{}

BSpeaker{}

Cstring{}

DPerson{}

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to assign a type that does not implement Speaker.

Only a value of type Person that implements Speaker can be assigned to s.

4fill in blank

hard

Fill both blanks to create a function that accepts any Speaker and calls Speak.

Go

func greet(s [1]) string { return s.[2]() }

Drag options to blanks, or click blank then click option'

ASpeaker

BPerson

CSpeak

DHello

Attempts:

3 left

💡 Hint

Common Mistakes

Using concrete type Person instead of interface Speaker in the function parameter.

Calling a method name not defined in the interface.

The function parameter type should be Speaker and call the Speak method.

5fill in blank

hard

Fill all three blanks to create a map of Speakers and call Speak on each.

Go

speakers := map[string][1]{
	"alice": [2]{},
}
for name, sp := range speakers {
	println(name, sp.[3]())
}

Drag options to blanks, or click blank then click option'

ASpeaker

BPerson

CSpeak

DHello

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong map value type.

Using wrong struct type for the map value.

Calling a method not defined in the interface.

The map holds values of interface type Speaker. The value is a Person struct. The method called is Speak.