Regular expressions with Regex class in Kotlin - Mini Project: Build & Apply

Regular expressions with Regex class

📖 Scenario: You are working on a simple text processing tool that needs to find specific patterns in user input. Regular expressions help you search for patterns like email addresses or phone numbers easily.

🎯 Goal: Build a Kotlin program that uses the Regex class to find all words starting with the letter 'a' in a given sentence.

📋 What You'll Learn

Create a string variable with a sentence containing multiple words

Create a Regex object to find words starting with 'a'

Use the findAll method of Regex to get all matches

Print all matched words separated by commas

💡 Why This Matters

🌍 Real World

Regular expressions are used in many apps to find patterns like emails, phone numbers, or keywords in text.

💼 Career

Knowing how to use Regex in Kotlin helps you build apps that process and validate text input efficiently.

1

Create the sentence string

Create a string variable called sentence and set it to the exact value: "An apple a day keeps the doctor away"

Kotlin

# Create a string variable called sentence with the given text
# Your code here

Need a hint?

Use val sentence = "An apple a day keeps the doctor away" to create the string.

2

Create the Regex pattern

Create a Regex object called pattern with the exact pattern "\\ba\\w*" to find words starting with the letter 'a'.

Kotlin

val sentence = "An apple a day keeps the doctor away"
# Create a Regex object called pattern with pattern "\\ba\\w*"
# Your code here

Need a hint?

Use val pattern = Regex("\\ba\\w*") to create the regex.

3

Find all matches using Regex

Use the findAll method of pattern on sentence and assign the result to a variable called matches.

Kotlin

val sentence = "An apple a day keeps the doctor away"
val pattern = Regex("\\ba\\w*")
# Use pattern.findAll(sentence) and assign to matches
# Your code here

Need a hint?

Use val matches = pattern.findAll(sentence) to get all matches.

4

Print all matched words

Print all matched words separated by commas by mapping matches to their value and joining them with ", " inside a println.

Kotlin

val sentence = "An apple a day keeps the doctor away"
val pattern = Regex("\\ba\\w*")
val matches = pattern.findAll(sentence)
# Print matched words separated by commas
# Your code here

Need a hint?

Use println(matches.map { it.value }.joinToString(", ")) to print the words.