Kotlin Basics: What is Kotlin? Features, History, Setup & Comparison with Java

1. What is Kotlin?

Kotlin is a modern, statically-typed programming language developed by JetBrains, designed to be fully interoperable with Java. It runs on the Java Virtual Machine (JVM), Android, and other platforms, offering concise syntax, null safety, and coroutines for asynchronous programming. Kotlin is the preferred language for Android development and is widely used for server-side, desktop, and multiplatform applications.

Key Advantages:

Use Case: Android apps, server-side APIs, cross-platform development.

2. History and Features of Kotlin

What is the History of Kotlin?

Kotlin was developed by JetBrains in 2010 as a modern alternative to Java, with the first stable release (Kotlin 1.0) in February 2016.

Milestones:

Philosophy: "Concise, safe, and pragmatic" – aims to improve Java while maintaining compatibility.

What are the Key Features of Kotlin?

3. Kotlin vs. Java Comparison

How Does Kotlin Compare to Java?

Aspect Kotlin Java
Syntax Concise, no semicolons, null safety Verbose, requires semicolons, no null safety
Null Safety Built-in (String? nullable) Manual checks (risk of NPE)
Interoperability 100% with Java Native (no interoperability needed)
Coroutines Native support for async Requires libraries (e.g., CompletableFuture)
Data Classes Built-in (data class) Manual implementation (POJOs)
Extension Functions Yes (add methods to classes) No (requires wrappers)
Performance Comparable (compiles to JVM bytecode) Comparable
Learning Curve Moderate (similar to Java) Steep for beginners
Android Development Preferred by Google Traditional

Advantages of Kotlin over Java:

4. Setting Up Environment: IntelliJ IDEA, Android Studio

How Do You Set Up the Kotlin Environment?

IntelliJ IDEA:

Android Studio:

Verification: Run kotlinc -version in terminal (after installing Kotlin compiler via SDKMAN or Homebrew).

Use Case: IntelliJ for desktop/multiplatform; Android Studio for mobile apps.

Example: Setting Up a Kotlin Project

// build.gradle.kts (Kotlin project setup)
plugins {
    kotlin("jvm") version "1.9.20"
    application
}

group = "com.example"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

dependencies {
    implementation(kotlin("stdlib"))
}

kotlin {
    jvmToolchain(17)
}

application {
    mainClass.set("MainKt")
}

// Main.kt (Kotlin program)
fun main() {
    println("Hello, Kotlin!")
    
    // Example class
    val person = Person("Krishna", 30)
    println(person.info())
}

class Person(val name: String, val age: Int) {
    fun info() = "Name: $name, Age: $age"
}
Output: Hello, Kotlin! Name: Krishna, Age: 30

Instructions:

Note: build.gradle.kts configures the project with Kotlin JVM plugin. Kotlin DSL (*.kts) is preferred for Gradle files in Kotlin projects.

5. Running Kotlin Programs (REPL, Command Line, IDE)

How Do You Run Kotlin Programs?

REPL (Kotlin REPL): Interactive shell for testing code snippets.

Command Line: Compile and run .kt files using kotlinc and kotlin.

IDE: Use IntelliJ IDEA or Android Studio for compilation and execution.

Use Case: REPL for prototyping; command line for scripts; IDE for projects.

Example: Running a Kotlin Program

// RunKotlinExample.kt (Simple program)
fun main() {
    val numbers = listOf(1, 2, 3, 4, 5)
    val sum = numbers.sum()
    println("Sum of numbers: $sum")
    
    // Function example
    val result = add(10, 20)
    println("Addition: $result")
}

fun add(a: Int, b: Int): Int {
    return a + b
}

Running Instructions:

Output: Sum of numbers: 15 Addition: 30

Note: REPL for interactive testing; command line for scripts; IDE for full projects. Kotlin compiles to JVM bytecode, running on Java runtime.

6. Common Mistakes and Best Practices

Common Mistakes:

Best Practices: