标签、占位符与前置图标
让输入框清晰易用。
标签、占位符与前置图标 是 CoddyKit 上的免费 Jetpack Compose Academy 课时。 这是第 2 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。
Make Inputs Friendly
A bare box leaves users guessing. Labels, placeholders, and icons turn a plain field into one that guides the user. 🧭
The label Slot
The label names the field. It sits inside when empty, then floats up to the border once the field is focused or filled.
OutlinedTextField(
value = email,
onValueChange = { email = it },
label = { Text("Email") }
)Add a Placeholder
A placeholder is hint text shown only while the field is empty. Use it for an example, not for the field's name.
placeholder = { Text("you@example.com") }Label vs Placeholder
The label always stays visible to identify the field. The placeholder vanishes the instant the user starts typing. Use both together.
Leading Icons
A leadingIcon sits at the start of the field. An envelope next to an email box makes its purpose obvious at a glance.
leadingIcon = {
Icon(Icons.Default.Email, contentDescription = null)
}Trailing Icons Too
A trailingIcon sits at the end. It is perfect for a clear button or a password visibility toggle.
trailingIcon = {
Icon(Icons.Default.Clear, contentDescription = "Clear")
}Always Describe Icons
Give each Icon a contentDescription so screen readers can announce it. Pass null only when the icon is purely decorative.
Make the Trailing Icon Tappable
Wrap a trailing icon in an IconButton so users can tap it, for example to clear the field in one touch.
trailingIcon = {
IconButton(onClick = { email = "" }) {
Icon(Icons.Default.Clear, "Clear")
}
}Supporting Text
supportingText shows a small hint below the field, like a format reminder or a character limit, without crowding the input.
supportingText = { Text("We never share your email.") }Combine Them Thoughtfully
Label plus icon plus a short placeholder is plenty. Too many hints add noise, so keep each field calm and clear.
Slots Are Just Composables
Every slot, like label and leadingIcon, is a lambda holding Composables. That means you can put any UI you want inside them.
Quick Check
When does a placeholder disappear from a text field?
Recap
You dressed up inputs with a label, placeholder hints, leading and trailing icons, and supporting text. Friendly fields, happy users. 😊
常见问题解答
「标签、占位符与前置图标」课时是免费的吗？
是的 — 「标签、占位符与前置图标」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。
「标签、占位符与前置图标」这节课中我会学到什么？
让输入框清晰易用。 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 2 节课，共 4 节。
「标签、占位符与前置图标」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。