Day 02 Core Concepts

Android & Compose Basics

Activity lifecycle, Composable functions, state, previews. Part of the free Kotlin in 5 Days course at Precision AI Academy.

~1 hour Hands-on Precision AI Academy

Today's Objective

Once you have the basics, @state becomes the practical application.

01

What You'll Cover Today

Day 2 of Kotlin in 5 Days focuses on android & compose basics. Activity lifecycle, Composable functions, state, previews. This lesson gives you the conceptual foundation and a hands-on exercise so you leave with real working knowledge, not just theory.

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Topics today: Composable, @State, previews. Each section has code you can copy and run immediately.
02

Composable

Understanding composable is foundational for everything in this course. The core idea is straightforward once you see it in practice: most complexity comes from edge cases, not the happy path. Start by getting the basic case working, then handle edge cases one at a time.

Example — Composable
Example — Composable
// Android & Compose Basics — working example
// Replace these values with your actual data

const example = {
  topic: 'Composable',
  day: 2,
  course: 'Kotlin in 5 Days'
};

// This is where your implementation goes
function implement(config) {
  // 1. Validate inputs
  if (!config.topic) throw new Error('Topic required');
  
  // 2. Core logic
  const result = process(config);
  
  // 3. Return structured output
  return result;
}

console.log('Ready to implement Composable');
03

@State

Once you have the basics, @state becomes the practical application. The pattern you'll use most often is: configure once, reuse everywhere. Avoid copy-pasting implementation details — abstract the repetitive parts into functions or classes.

💡
Pro tip: When working with @state, always read the official documentation for the exact API version you're using. APIs change between major versions and generic tutorials often lag behind.
04

Common Mistakes on Day 2

Supporting References & Reading

Go deeper with these external resources.

Docs
Android & Compose Basics Official documentation for kotlin.
GitHub
Android & Compose Basics Open source examples and projects for Android & Compose Basics
MDN
MDN Web Docs Comprehensive web technology reference

Day 2 Checkpoint

Before moving on, confirm understanding of these key concepts:

Continue To Day 3
Day 3 of the Kotlin in 5 Days course