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从 Composable 调用 Composable

将小片段组合成更大的屏幕。

从 Composable 调用 Composable 是 CoddyKit 上的免费 Jetpack Compose Academy 课时。这是第 3 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 Jetpack Compose Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Jetpack Compose 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。

Build Big From Small

Real screens are not one giant function. You compose them by calling small Composables from inside larger ones, like nesting building blocks. 🧱

A Composable Calls Another

Inside one Composable you simply call another by name. Here Screen calls Greeting, and Compose draws Greeting where you placed it.

@Composable
fun Screen() {
    Greeting("Compose")
}

Stack Several Calls

List multiple calls one after another and they render in order, top to bottom, just like reading down the function.

@Composable
fun Screen() {
    Header()
    Body()
    Footer()
}

The Composition Tree

These nested calls form a tree. Screen is the parent, and each Composable it calls becomes a child node in the UI hierarchy.

Pass Data Downward

Parents hand data to children through parameters. The parent owns the value and the child just displays what it receives.

@Composable
fun Screen() {
    UserName(name = "Ada")
}

Reuse Everywhere

Because a Composable is just a function, you can reuse it as many times as you like across different screens with different data.

@Composable
fun List() {
    Item("Apple")
    Item("Pear")
}

Extract to Stay Readable

When a function grows long, extract a chunk into its own Composable and call it. The screen reads like a clear outline.

Composables Compose

The name says it all: small pieces combine into bigger ones. Mastering this nesting is the heart of building any Compose UI.

Children Render in Place

A child appears exactly where you call it in the parent. Move the call up or down and the UI moves with it.

@Composable
fun Card() {
    Title()
    Divider()
    Title()
}

Mix Built-in and Custom

You freely mix framework Composables like Text with your own. Compose treats them all the same when building the tree.

@Composable
fun Card() {
    Text("Hi")
    Greeting("there")
}

Think in Components

Designing in Compose means thinking in small reusable components. Each owns one job, and screens become a tidy arrangement of them.

Quick Check

Quick check on composing Composables.

Recap

You can now build screens by nesting Composables: call small ones inside bigger ones, pass data down, and reuse components to form the UI tree. 🎉

常见问题解答

「从 Composable 调用 Composable」课时是免费的吗？

是的 — 「从 Composable 调用 Composable」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 Jetpack Compose Academy 课程的其余内容，请升级到 CoddyKit PRO。 Jetpack Compose Academy 课程共包含 4 节课。

「从 Composable 调用 Composable」这节课中我会学到什么？

将小片段组合成更大的屏幕。你通过在浏览器中直接运行的动手代码来练习 Jetpack Compose 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 Jetpack Compose Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Jetpack Compose 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 3 节课，共 4 节。

「从 Composable 调用 Composable」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 Jetpack Compose Academy 课中编写并运行代码吗？

能。每节 Jetpack Compose 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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