Step-by-Step Explanation: Kotlin Basic Types

This document explains how to work with Kotlin's basic types and the compiler's type inference engine.

1. Type Inference

Kotlin is statically typed, but you don't always have to write the type. The compiler looks at the value you assign and "infers" the type.

• Example: var customers = 10 is automatically an Int.
• Once inferred, the variable behaves strictly as that type. You can perform arithmetic on Int, but you couldn't assign a String to it later.

2. Explicit Type Declaration

If you need a specific type (like Long instead of Int) or just want to be explicit, use the : Type syntax.

val year: Int = 2020
val amount: Long = 350_000_000L
val currentTemp: Float = 24.5f

Key Differences from Java:

• Suffixes: Like Java, Long needs an L suffix and Float needs an f.
• Unsigned Types: Kotlin supports unsigned types like UInt (e.g., 100u).
• Readability: You can use underscores in numbers: 1_000_000.

3. Deferred Initialization

Kotlin allows you to declare a variable without a value, but you must specify the type. The compiler also tracks if you've initialized it before use.

val d: Int // Type is required here
d = 3      // Initialized later

4. Interop with Java

All these types map directly to Java types (either primitives or wrappers). When calling from Java, top-level functions in BasicTypes.kt are accessed via BasicTypesKt.

5. Verification

The implementation was verified by building the project with ./gradlew :app:assemble and running the application to see the values printed in the console.