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YOUR KOTLIN LEARNING PATH

A little more Kotlin.
A little more confidence.

One idea at a time, with examples you can follow and checkpoints to see what’s clicking. New here? Begin with chapter one. Know a little already? Jump right in.

Before you start

Basic variables, functions, and collections are helpful. The early chapters introduce Kotlin expressions and control flow before null safety, classes, and advanced APIs.

Review a foundation whenever you need it: First Python program · Decisions and loops · Small functions

Start chapter one Ready for the final?
13 open chapters. Your progress is saved as you go.

Your chapters

Choose any starting point
  1. 01

    Values and functions

    Beginner

    Express small computations with typed parameters and returned values.

    Start here, or skip ahead
    Open chapter: Values and functions
  2. 02

    Conditions, ranges, and iteration

    Beginner

    Use expression results and precise loop bounds.

    Open whenever you’re ready
    Open chapter: Conditions, ranges, and iteration
  3. 03

    Text transformations and search boundaries

    Intermediate

    Normalize text while preserving the intended meaning of positions.

    Open whenever you’re ready
    Open chapter: Text transformations and search boundaries
  4. 04

    Null safety and validation

    Intermediate

    Make absent values explicit before using them.

    Open whenever you’re ready
    Open chapter: Null safety and validation
  5. 05

    Arrays and two-dimensional traversal

    Intermediate

    Calculate row and column results with explicit shape assumptions.

    Open whenever you’re ready
    Open chapter: Arrays and two-dimensional traversal
  6. 06

    Collections and transformations

    Intermediate

    Separate read-only access from mutability and compose useful operations.

    Open whenever you’re ready
    Open chapter: Collections and transformations
  7. 07

    Maps, sets, and occurrence policies

    Intermediate

    Aggregate by keys without confusing missing data and zero totals.

    Open whenever you’re ready
    Open chapter: Maps, sets, and occurrence policies
  8. 08

    Higher-order functions and captured state

    Advanced

    Trace functions as values and make closure state explicit.

    Open whenever you’re ready
    Open chapter: Higher-order functions and captured state
  9. 09

    Classes and data values

    Intermediate

    Model identity and understand what generated copying does.

    Open whenever you’re ready
    Open chapter: Classes and data values
  10. 10

    Interfaces and sealed alternatives

    Advanced

    Represent interchangeable behavior and closed sets of outcomes.

    Open whenever you’re ready
    Open chapter: Interfaces and sealed alternatives
  11. 11

    Generic APIs and variance

    Advanced

    Express reusable producer and consumer capabilities safely.

    Open whenever you’re ready
    Open chapter: Generic APIs and variance
  12. 12

    Lazy sequences and bounded evaluation

    Advanced

    Predict which transformations actually execute.

    Open whenever you’re ready
    Open chapter: Lazy sequences and bounded evaluation
  13. 13

    Validation, failures, and contract tests

    Advanced

    Reject unsupported input without corrupting state.

    Open whenever you’re ready
    Open chapter: Validation, failures, and contract tests

PUT IT TOGETHER

Final assessment & certificate

30 multiple-choice questions and 2 written coding problems. Pass the knowledge section at 80% overall and at least 50% in every chapter area, complete and review the written practice, and meet the attempt-integrity checks to unlock your certificate.

The certificate records a CodeQuest foundations assessment. Written work is self-reviewed; identity and independent proficiency are not verified.

Open final assessment

Take an issuer-recorded assessment with a verifiable certificate

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