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为您的领域建模使用数据类

免费获得带有 copy 和 equals 的不可变共享模型

为您的领域建模使用数据类 是 CoddyKit 上的免费 Kotlin Multiplatform Academy 课时。这是第 1 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Kotlin Multiplatform Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Kotlin Multiplatform Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Your Domain Needs Models

Every app describes real things like users, orders or songs. In KMP you model them once with shared data classes.

Meet the data class

A data class is a small type built to hold values. You add the keyword and list the properties in the header.

data class User(val id: Int, val name: String)

It Lives in commonMain

Put your model in commonMain and both the Android and iOS apps see the exact same shape with no duplication.

// shared/src/commonMain
data class User(val id: Int, val name: String)

Create an Instance

Build a model by calling it like a function and passing each value. The object now carries your data everywhere.

val ada = User(id = 1, name = "Ada")

Read the Properties

Access any field with a dot. Reading properties works the same in shared code, Android and iOS.

val label = ada.name + " #" + ada.id

Free toString

A data class auto-generates a readable toString, so printing a model shows its values instead of a cryptic address.

println(ada) // User(id=1, name=Ada)

Value-Based equals

Two models with the same fields are considered equal. Data classes compare by content, not by memory identity.

User(1, "Ada") == User(1, "Ada") // true

Copy with Changes

The free copy function clones a model while overriding only the fields you name, keeping the original untouched.

val renamed = ada.copy(name = "Grace")

Prefer Immutable val

Declare fields as val so models cannot change after creation. Immutable data is safer to share across platforms.

data class Song(val title: String, val seconds: Int)

Compose Models Together

A model can hold other models as fields, letting you nest data classes to mirror real relationships in your domain.

data class Playlist(val owner: User, val songs: List<Song>)

Why This Matters

One shared model means Android and iOS can never disagree about your data shape, killing a whole class of bugs. 🙂

Quick Check

Which free feature did the data class give you here?

Recap

Shared data classes in commonMain give you copy, equals and toString for free, modeling your domain once for both apps.

常见问题解答

「为您的领域建模使用数据类」课时是免费的吗？

是的 — 「为您的领域建模使用数据类」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Kotlin Multiplatform Academy 课程的其余内容，请升级到 CoddyKit PRO。 Kotlin Multiplatform Academy 课程共包含 4 节课。

「为您的领域建模使用数据类」这节课中我会学到什么？

免费获得带有 copy 和 equals 的不可变共享模型你通过在浏览器中直接运行的动手代码来练习 Kotlin Multiplatform Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Kotlin Multiplatform Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Kotlin Multiplatform Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 1 节课，共 4 节。

「为您的领域建模使用数据类」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Kotlin Multiplatform Academy 课中编写并运行代码吗？

能。每节 Kotlin Multiplatform Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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