When with ranges and types in Kotlin - Mini Project: Build & Apply

Using When with Ranges and Types in Kotlin

📖 Scenario: You are building a simple program that categorizes input values based on their type and numeric range. This is useful in many apps where you want to respond differently depending on what kind of data you get and its value.

🎯 Goal: Create a Kotlin program that uses a when expression to check both the type and the numeric range of a variable, then prints a message describing the input.

📋 What You'll Learn

Create a variable called input with a specific value.

Create a variable called ageRange representing ages from 13 to 19 inclusive.

Use a when expression to check the type of input and if it is an Int, check if it falls within ageRange.

Print the correct message based on the checks.

💡 Why This Matters

🌍 Real World

Checking input types and ranges is common in apps that need to validate user data, like age verification or input validation.

💼 Career

Understanding how to use <code>when</code> with types and ranges helps you write clear and concise Kotlin code for decision making, a key skill for Android and backend Kotlin developers.

1

Create the input variable

Create a variable called input and set it to the integer value 16.

Kotlin

# Create a variable called input and set it to 16
# Your code here

Need a hint?

Use val input: Any = 16 to allow different types later.

2

Create the ageRange variable

Create a variable called ageRange that represents the range of integers from 13 to 19 inclusive.

Kotlin

val input: Any = 16
# Create a variable called ageRange for numbers 13 to 19 inclusive
# Your code here

Need a hint?

Use the range operator .. to create the range.

3

Write the when expression to check type and range

Write a when expression using the variable input that checks:
- If input is an Int and is in ageRange, print "Teenager".
- If input is an Int but not in ageRange, print "Not a teenager".
- If input is a String, print "Input is a string".
- For any other type, print "Unknown type".

Kotlin

val input: Any = 16
val ageRange = 13..19

// Write a when expression to check input type and range
// Your code here

Need a hint?

Use is to check type and in to check if number is in range.

4

Print the result

Run the program to print the correct message based on the input value and the when expression.

Kotlin

val input: Any = 16
val ageRange = 13..19

when (input) {
    is Int -> if (input in ageRange) {
        println("Teenager")
    } else {
        println("Not a teenager")
    }
    is String -> println("Input is a string")
    else -> println("Unknown type")
}

// Run the program to see the output
# Your code here

Need a hint?

Running the program should print "Teenager" because 16 is in the range 13 to 19.