Adding questions
- Kotlin course
- Intermediate
- Lesson 43/116
- 6 min
Learn to add questions with the addQuestion function.
Adding questions
In the second lesson we add the addQuestion function. It takes a question text and an answer, and adds a new Question to the list.
Example: fun addQuestion(text: String, answer: String) { questions.add(Question(text, answer)) }. This function is called as addQuestion("2+2?", "4"). The questions list is declared at file scope, so the function reaches it directly. To add multiple questions you call the function again. The data model and list come from the first lesson; this lesson only adds the function.
Adding multiple questions
Each call to addQuestion grows the list. Every call adds a new Question instance.
Example: addQuestion("Capital city?", "Ankara"); addQuestion("2+2?", "4"). After these two calls questions has two items. Calling println(questions) prints [Question(text=Capital city?, answer=Ankara), Question(text=2+2?, answer=4)]. Thanks to the data class's automatic toString, the list content is readable.
Practice Add two questions with addQuestion
Build on the first lesson's solution: data class Question(val text: String, val answer: String) and val questions: MutableList<Question> = mutableListOf() are defined. Add a fun addQuestion(text: String, answer: String) function whose body does questions.add(Question(text, answer)). In main call addQuestion("Capital city?", "Ankara") and addQuestion("2+2?", "4"), then print the list with println(questions).
Starter code
data class Question(val text: String, val answer: String)
val questions: MutableList<Question> = mutableListOf()
// add the addQuestion function: takes text and answer, adds a Question to the list
fun main() {
// add two questions and print the list
}Sample solution
data class Question(val text: String, val answer: String)
val questions: MutableList<Question> = mutableListOf()
fun addQuestion(text: String, answer: String) {
questions.add(Question(text, answer))
}
fun main() {
addQuestion("Capital city?", "Ankara")
addQuestion("2+2?", "4")
println(questions)
}Expected output
[Question(text=Capital city?, answer=Ankara), Question(text=2+2?, answer=4)]
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Complete the addQuestion function
fun addQuestion(text: String, answer: String) {
questions.____(Question(text, answer))
}fun addQuestion(text: String, answer: String) {
questions.add(Question(text, answer))
}Explanation: questions.add adds a new question.
2 Match the addQuestion parts
| Term | Meaning |
|---|---|
fun addQuestion(text, answer) |
Function signature |
questions.add |
List append |
Question(text, answer) |
New question instance |
addQuestion("2+2?", "4") |
Call |
3 How does the <code>addQuestion</code> function access the <code>questions</code> list?
- It takes it as a parameter
- Through a singleton
- Directly, because it is declared at file scope Correct answer
- From a companion object
Explanation: questions is declared at file scope; the function reaches it directly.