Exercise: User Information Processor
Implement the processUserInformation function according to the following rules:
- If the input
userisnull, return"Missing user information". - If
namefromuserisnull, throw anIllegalArgumentException. - If
agefromuserisnull, treat it as 0. - If
emailfromuserisnullor contains a blank email address, return"Missing email". - Otherwise, return information about user in the following format: "User {name} is {age} years old, email: {email}".
Starting code:
fun processUserInformation(user: User?): String {
return ""
}
data class EmailAddress(val email: String?)
data class User(
val name: String?,
val age: Int?,
val email: EmailAddress?
)
Example usage:
println(processUserInformation(null))
// Missing user information
val user1 = User(
"John",
30,
EmailAddress("john@example.com")
)
println(processUserInformation(user1))
// User John is 30 years old, email: john@example.com
val user2 = User(
"Alice",
null,
EmailAddress("alice@example.com")
)
println(processUserInformation(user2))
// User Alice is 0 years old, email: alice@example.com
val user3 = User(
"Bob",
25,
EmailAddress("") // or EmailAddress(null) or null
)
println(processUserInformation(user3))
// Missing email
val user6 = User(
null,
40,
EmailAddress("jake@example.com")
)
println(processUserInformation(user6))
// IllegalArgumentException
This problem can either be solved in the below playground or you can clone kotlin-exercises project and solve it locally. In the project, you can find code template for this exercise in essentials/nullability/UserInformation.kt. You can find there starting code, example usage and unit tests.
Once you are done with the exercise, you can check your solution here.
Playground
import org.junit.Assert.assertThrows
import org.junit.Test
import kotlin.test.assertEquals
fun processUserInformation(user: User?): String {
return ""
}
data class EmailAddress(val email: String?)
data class User(
val name: String?,
val age: Int?,
val email: EmailAddress?
)
fun main() {
println(processUserInformation(null))
// Missing user information
val user1 = User(
"John",
30,
EmailAddress("john@example.com")
)
println(processUserInformation(user1))
// User John is 30 years old, email: john@example.com
val user2 = User(
"Alice",
null,
EmailAddress("alice@example.com")
)
println(processUserInformation(user2))
// User Alice is 0 years old, email: alice@example.com
val user3 = User(
"Bob",
25,
EmailAddress("") // or EmailAddress(null) or null
)
println(processUserInformation(user3))
// Missing email
val user6 = User(
null,
40,
EmailAddress("jake@example.com")
)
println(processUserInformation(user6))
// IllegalArgumentException
}
class StudentInformationTest {
@Test
fun `valid user information`() {
val user = User("John Doe", 30, EmailAddress("john@example.com"))
val result = processUserInformation(user)
val expected = "User John Doe is 30 years old, email: john@example.com"
assertEquals(expected, result)
}
@Test
fun `null user information`() {
val result = processUserInformation(null)
val expected = "Missing user information"
assertEquals(expected, result)
}
@Test
fun `user with missing age should have age 0`() {
val user = User("Alice", null, EmailAddress("alice@example.com"))
val result = processUserInformation(user)
val expected = "User Alice is 0 years old, email: alice@example.com"
assertEquals(expected, result)
}
@Test
fun `user with blank email`() {
val user = User("Bob", 25, EmailAddress(""))
val result = processUserInformation(user)
val expected = "Missing email"
assertEquals(expected, result)
}
@Test
fun `user with null email address`() {
val user = User("Bob", 25, EmailAddress(null))
val result = processUserInformation(user)
val expected = "Missing email"
assertEquals(expected, result)
}
@Test
fun `user with null email information`() {
val user = User("Bob", 25, null)
val result = processUserInformation(user)
val expected = "Missing email"
assertEquals(expected, result)
}
@Test
fun `user with missing name should throw exception`() {
val user = User(null, 40, EmailAddress("email@example.com"))
assertThrows(IllegalArgumentException::class.java) {
processUserInformation(user)
}
}
}
