In the previous tutorial, you learned what Kotlin is and why developers love it. Now it is time to install Kotlin on your computer and write your first program. In this tutorial, you will: Install IntelliJ IDEA (the best IDE for Kotlin) Create a Kotlin project Write and run your first programs Try the Kotlin REPL Use the Kotlin Playground (no installation needed) Option 1: Kotlin Playground (No Installation) If you want to try Kotlin right now without installing anything, go to the Kotlin Playground. ...

In the previous tutorial, you installed Kotlin and wrote your first programs. Now let’s learn about variables and types — the building blocks of every Kotlin program. In this tutorial, you will learn: The difference between val and var All basic types in Kotlin How type inference works How to convert between types How to use constants with const val val vs var Kotlin has two keywords for declaring variables: ...

In the previous tutorial, you learned about variables and types. Now let’s learn about null safety — the feature that makes Kotlin truly special. NullPointerException (NPE) is the most common crash in Java and many other languages. Tony Hoare, who invented null references in 1965, called it his “billion-dollar mistake”. Kotlin solves this problem at compile time. ...

In the previous tutorial, you learned about null safety. Now let’s learn about functions — the building blocks that organize your code into reusable pieces. Kotlin functions are more powerful than Java methods. They support default parameters, named arguments, single-expression syntax, and much more. In this tutorial, you will learn: ...

In the previous tutorial, you learned about functions. Now let’s learn about control flow — how to make decisions and repeat actions in your code. Kotlin’s control flow is similar to Java, but with important improvements. if and when are expressions that return values. when replaces switch and is much more powerful. ...

In the previous tutorial, you learned about control flow. Now let’s learn about classes — the foundation of object-oriented programming in Kotlin. Kotlin classes are more concise than Java classes. What takes 50 lines in Java takes 1 line in Kotlin with data classes. In this tutorial, you will learn: ...

Two years ago, AI tools for developers meant one thing: autocomplete. Now they do everything — write code, review code, create designs, generate tests, manage databases, deploy apps, and even write documentation. Here are the 10 AI tools I actually use. Not tools I read about. Tools that are open on my computer right now. 1. Cursor — The Code Editor What it does: AI-powered code editor that writes, edits, and refactors code. ...

Bookmark this page. Use Ctrl+F (or Cmd+F on Mac) to find what you need. This cheat sheet covers Jetpack Compose components, modifiers, state, navigation, and common patterns. Last updated: April 2026 Core Composables Composable Usage Text("Hello") Display text Text("Bold", fontWeight = FontWeight.Bold) Styled text Button(onClick = { }) { Text("Click") } Clickable button OutlinedButton(onClick = { }) { Text("Outlined") } Outlined variant TextButton(onClick = { }) { Text("Text") } Text-only button IconButton(onClick = { }) { Icon(...) } Icon button TextField(value, onValueChange = { }) Text input field OutlinedTextField(value, onValueChange = { }) Outlined text input Image(painter, contentDescription) Display an image Icon(Icons.Default.Home, contentDescription) Material icon Checkbox(checked, onCheckedChange) Checkbox Switch(checked, onCheckedChange) Toggle switch RadioButton(selected, onClick) Radio button Slider(value, onValueChange) Slider CircularProgressIndicator() Loading spinner LinearProgressIndicator(progress) Progress bar HorizontalDivider() Horizontal divider line (replaces deprecated Divider()) Spacer(modifier = Modifier.height(16.dp)) Empty space Layouts // Column — vertical stack Column { Text("First") Text("Second") } // Row — horizontal stack Row { Text("Left") Spacer(Modifier.weight(1f)) Text("Right") } // Box — stack on top of each other Box { Image(...) // background Text("Overlay") // on top } // LazyColumn — scrollable vertical list (RecyclerView replacement) LazyColumn { items(list) { item -> Text(item.name) } } // LazyRow — scrollable horizontal list LazyRow { items(list) { item -> Card { Text(item.name) } } } // LazyVerticalGrid — grid layout LazyVerticalGrid(columns = GridCells.Fixed(2)) { items(list) { item -> Card { Text(item.name) } } } Common Modifiers Modifiers change the appearance and behavior of composables. Order matters — modifiers are applied top to bottom. ...

Every app has lists. A chat app has a list of messages. A store app has a list of products. A settings app has a list of options. In the old Android world, you used RecyclerView — which needed an Adapter, a ViewHolder, a LayoutManager, and a lot of boilerplate code. In Compose, you just use LazyColumn. That’s it. LazyColumn vs Column — Why Not Just Use Column? You already know Column from Tutorial #2. Why not use it for lists? ...

You open Claude Code on a new project. You ask it to fix a bug. It changes the wrong file. It uses the wrong architecture pattern. It runs the wrong build command. Not because Claude is bad. Because it doesn’t know your project. That is what context files solve. A CLAUDE.md or AGENTS.md file tells the AI everything it needs to know about your project before it starts working. It is the single most impactful thing you can do to improve AI coding agent output. ...