Launch coroutine builder in Kotlin - Mini Project: Build & Apply

Launch Coroutine Builder

📖 Scenario: You are building a simple Kotlin program that uses coroutines to perform a task asynchronously. This is useful when you want to run code without blocking the main thread, like loading data or doing background work.

🎯 Goal: Create a Kotlin program that launches a coroutine using the launch coroutine builder to print a message asynchronously.

📋 What You'll Learn

Create a main function

Use runBlocking to start the coroutine scope

Launch a coroutine using launch

Inside the coroutine, print the message "Hello from coroutine!"

Print "Hello from main!" in the main thread

💡 Why This Matters

🌍 Real World

Coroutines help run tasks like network calls or file operations without freezing the app interface.

💼 Career

Understanding coroutine builders like <code>launch</code> is essential for Kotlin developers working on Android or backend applications to write efficient asynchronous code.

1

Create the main function with runBlocking

Write a main function that uses runBlocking to create a coroutine scope.

Kotlin

import kotlinx.coroutines.runBlocking

fun main() = runBlocking {
    // Your code here
}

Need a hint?

Use fun main() = runBlocking { } to start your coroutine scope.

2

Launch a coroutine inside runBlocking

Inside the runBlocking block, launch a coroutine using launch.

Kotlin

import kotlinx.coroutines.launch

import kotlinx.coroutines.runBlocking

fun main() = runBlocking {
    // Launch a coroutine here
}

Need a hint?

Use launch { } inside runBlocking to start a coroutine.

3

Print a message inside the coroutine

Inside the launch coroutine, write a println statement to print "Hello from coroutine!".

Kotlin

import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking

fun main() = runBlocking {
    launch {
        // Print message here
    }
}

Need a hint?

Use println("Hello from coroutine!") inside the launch block.

4

Print a message in the main thread

After launching the coroutine, write a println statement in the runBlocking block to print "Hello from main!".

Kotlin

import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking

fun main() = runBlocking {
    launch {
        println("Hello from coroutine!")
    }
    // Print message from main here
}

Need a hint?

Use println("Hello from main!") after the launch block inside runBlocking.