Capstoneintermediate5h

Kotlin Note-Taking Data Model

Design (on paper/in guided steps, since this platform can't execute Kotlin) the data model and core logic for a note-taking app in Kotlin, applying data classes, null safety, and collections.

Tracks: Kotlin Fundamentals

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Objectives

Design a Note data class (id, title, body, completed) with a default value for completed
Write a findNote(id) function returning Note? and handle the missing case with ?./?: at every call site
Write functions to add a note (returning a new list) and mark one complete (using copy(), not mutation)
Use filter to list only incomplete notes

Before you start

Milestones

1. Design the Note data class

Define a Note data class with sensible defaults.

Note is declared as a data class with id, title, body, and completed fields
completed defaults to false so callers creating a new note don't need to specify it

2. A null-safe lookup function

Write findNote(notes, id): Note? and use ?./?: wherever it's called.

findNote's return type is honestly Note?, not Note
Every call site handles the null case with ?. or ?:, never !!

3. Add and complete without mutation

Write addNote (returns a new list) and completeNote (uses copy(), not in-place mutation).

addNote returns a new List<Note> rather than mutating the original in place
completeNote uses copy(completed = true) rather than reassigning a var field

4. Filter incomplete notes

Write a function using filter to return only notes where completed is false.

The filter lambda checks !it.completed (or equivalent)
The function's return type is List<Note>

References

Kotlin documentation