Kotlin program: Convert list of strings to uppercase with lambda

Last update on February 04 2025 11:07:19 (UTC/GMT +8 hours)

Write a Kotlin program that implements a lambda expression to convert a list of strings to uppercase.

Pre-Knowledge (Before You Start!)

Before solving this exercise, you should be familiar with the following concepts:

• Lambda Expressions: A lambda expression is an anonymous function that allows concise operations on collections.
• String Manipulation: The uppercase() function converts a string to uppercase.
• Mapping Collections: The map() function transforms each element in a collection based on a given lambda expression.
• Iteration: The forEach function is used to iterate through a list and perform an operation on each element.

Hints (Try Before Looking at the Solution!)

Here are some hints to help you solve the problem:

• Hint 1: Create a list of lowercase strings.
• Hint 2: Use the map() function to apply a transformation to each string.
• Hint 3: Inside the lambda expression, use the uppercase() function to convert each string to uppercase.
• Hint 4: Store the transformed list in a variable.
• Hint 5: Use forEach to iterate over the transformed list and print each string on a new line.

Sample Solution:

Kotlin Code:

fun main() {
    val strings = listOf("red", "green", "blue", "white", "orange", "black")

    val uppercaseList = strings.map { it.uppercase() }

    println("Uppercase List:")
    uppercaseList.forEach { println(it) }
}

Sample Output:

Uppercase List:
RED
GREEN
BLUE
WHITE
ORANGE
BLACK

Explanation:

In the above exercise -

• We have a list of strings called "strings". We use the map function on the "strings" list and provide a lambda expression { it.toUpperCase() } as the mapping operation.
• Inside the lambda expression, we call the toUpperCase function on each string (it) to convert it to uppercase.
• The "map()" function applies the lambda expression to each element of the "strings" list and returns a new list with transformed uppercase strings.
• Finally, we print the uppercase list using println and forEach to iterate over each string in the uppercase list. We print it on a separate line.

Kotlin Editor:

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