Add Kotlin Parcelize snippets

[erikrodriguez-se]

Snippets migration - Kotlin parcelize

Snippets for the Parcelize guide at developer.android.com/kotlin/parcelize, extracted into kotlin/src/main/kotlin/com/example/android/basics/ (Parcelize.kt and ParcelizeDataClass.kt) with region tags, plus the parcelize plugin in kotlin/build.gradle.kts.

Thirteen of the page's 24 code blocks are extracted. Most are verbatim; the differences that exist fall into three kinds, described below.

Region tag (android_kotlin_parcelize_*)	Page section	Verbatim	Deviation	Rendered / page
_basic	intro	no	import shown as a comment; colon spacing	4 / 4
_companion_parceler	intro	yes	—	12 / 12
_external_class_parceler	Custom Parcelers	yes	—	9 / 9
_type_parceler_class	Custom Parcelers	yes	—	4 / 4
_type_parceler_property	Custom Parcelers	yes	—	3 / 3
_type_parceler_type	Custom Parcelers	yes	—	3 / 3
_parcelable_creator	Create data from Parcel	no	import shown as a comment	5 / 5
_ignored_on_parcel	Skip properties from serialization	no	colon spacing	10 / 10
_raw_value	Parcel.writeValue	no	colon spacing	2 / 2
_sealed_class	Sealed classes and interfaces	no	colon spacing ×5	8 / 8
_data_class	Experimental / Data class serializer	no	@file:OptIn shown as a comment	6 / 6
_data_class_wrapper	Experimental / Data class serializer	no	colon spacing	8 / 8
_inheritance_base	Experimental / Non val or var params	no	colon spacing ×2	11 / 11

The three kinds of deviation

Colon spacing. The page writes ): Parcelable; this repo's ktlint config rewrites it to ) : Parcelable. This is unavoidable — spotlessApply makes the change when run — and it accounts for most of the non-verbatim rows above.

File-top declarations shown as a comment. The _basic and _parcelable_creator blocks open with an import, and _data_class opens with @file:OptIn(kotlinx.parcelize.Experimental::class). Kotlin requires those at the top of the file, above the package declaration and outside any snippet region. To keep them visible in the published snippet, the real line lives at the top of the file (uncommented, so it compiles) and a commented copy is placed inside the region. The published snippet therefore shows, for example, // import kotlinx.parcelize.Parcelize where the page currently shows a live import statement. The page's blocks would be updated to match.

One experimental block omitted. The page's "Non val or var parameters" section has two code blocks: _inheritance_base (the non-experimental approach, extracted) and an experimental variant that requires experimentalCodeGeneration=true. That flag is a parcelize compiler-plugin argument with module-level granularity — it cannot be scoped to a single snippet, and enabling it module-wide would compile the kotlin module's unrelated snippets (coroutines, flow testing) under experimental codegen. The experimental block is therefore not extracted, and the flag is not set. _inheritance_base alone still demonstrates the section's point.

Code not extracted

• Gradle config — the Groovy plugins block (this repo is Kotlin DSL only), the Kotlin DSL plugins block, the additionalAnnotation block and the experimentalCodeGeneration block. Build-config blocks are published in their portable id("…") form on the page rather than this repo's version-catalog form, so they are left hand-maintained.
• Java — the UserCreator block under Create data from Parcel. Kotlin only.
• Multiplatform — all four expect/actual blocks under Setup Parcelize for Kotlin multiplatform. Will not compile in a plain Android module.
• The experimental inheritance block and the // ERROR: not allowed example, both under Non val or var parameters in primary constructor. See "One experimental block omitted" above; the ERROR example cannot compile by design.

Deprecations

None. Ten imports, all current — android.os.Parcel, android.os.Parcelable and eight kotlinx.parcelize symbols. A forced full recompile produced zero warnings.

[snippet-bot]

Here is the summary of changes.

You are about to add 13 region tags.

• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:31, tag android_kotlin_parcelize_basic
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:40, tag android_kotlin_parcelize_companion_parceler
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:60, tag android_kotlin_parcelize_external_class_parceler
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:84, tag android_kotlin_parcelize_type_parceler_class
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:103, tag android_kotlin_parcelize_type_parceler_property
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:121, tag android_kotlin_parcelize_type_parceler_type
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:132, tag android_kotlin_parcelize_parcelable_creator
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:142, tag android_kotlin_parcelize_ignored_on_parcel
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:159, tag android_kotlin_parcelize_raw_value
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:166, tag android_kotlin_parcelize_sealed_class
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:179, tag android_kotlin_parcelize_data_class_wrapper
• kotlin/src/main/kotlin/com/example/android/basics/Parcelize.kt:192, tag android_kotlin_parcelize_inheritance_base
• kotlin/src/main/kotlin/com/example/android/basics/ParcelizeDataClass.kt:26, tag android_kotlin_parcelize_data_class

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[erikrodriguez-se]

Not in the original fork PR but this is a linter nit worth addressing since we're touching the file