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Walkthrough - Kotlin Tour: Libraries & APIs

Walkthrough - Kotlin Tour: Libraries & APIs

In this lesson, we explored Kotlin's standard library and how to integrate external libraries like kotlinx-datetime. We also covered time measurement, math functions, and opt-in APIs.

Changes Made

Configuration

  • Added kotlinx-datetime to libs.versions.toml.
  • Added implementation(libs.kotlinx.datetime) to build.gradle.kts.
  • Performed a Gradle sync to download the new dependency.

Implementation

  • Created LibrariesAndAPIs.kt which implements:
    • Standard Library: Demonstrating implicitly imported functions like reversed().
    • Time Measurement: Using kotlin.time with extension properties (30.minutes) and measureTime.
    • External Libraries: Using kotlinx-datetime to get the current time and handle time zones.
    • Opt-in APIs: Using @OptIn to access experimental unsigned types (UIntArray).
    • Exercises:
      • Compound interest calculation using kotlin.math.pow.
      • Measuring execution time of a data processing block.
  • Updated App.java to execute these demonstrations.

Verification

  • Build: Successfully executed ./gradlew :app:assemble.
  • Logic: Verified that 30.minutes == 0.5.hours and that external date-time logic returns the correct current instant.

See the Step-by-Step Explanation for technical details.

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