kotlin 中数据绑定的好处？
Benefits of Databinding in kotlin?
我想知道在开发 Android 应用程序时编写额外代码以在 Kotlin 中实现数据绑定的好处。
因为 Kotlin 扩展已经允许我们直接访问视图而不需要 findViewById。
我找到了答案here:
Hey! Developer Advocate for Android at Google here!
I wanted to add a bit of background here. Kotlin Extensions with synthetic views was never intentionally “recommended” though that shouldn’t be taken as a recommendation to not use them. If they're working for you please feel free to continue using them in your app!
We’ve been shifting away from them (e.g. we don’t teach them in the Udacity course) because they expose a global namespace of ids that’s unrelated to the layout that’s actually inflated with no checks against invalid lookups, are Kotlin only, and don't expose nullability when views are only present in some configuration. All together, these issues cause the API to increase number of crashes for Android apps.
On the other hand, they do offer a lightweight API that can help simplify view lookups. In this space it's also worth taking a look at Data Binding which also does automatic view lookups - as well as integrates with LiveData to automatically update your views as data changes.
Today, there's a few options in this space that work:
- Data Binding is the recommendation for view lookup as well as binding, but it does add a bit of overhead when compared to Android Kotlin Extensions. It's worth taking a look to see if this is a good fit for your app. Data Binding also allows you to observe LiveData to bind views automatically when data changes. Compared to Kotlin Extensions, it adds compile time checking of view lookups and type safety.
- Android Kotlin Extensions is not officially recommended (which is not the same as recommendation against). It does come with the issues mentioned above, so for our code we're not using them.
- Butter Knife is another solution that is extremely popular and works for both Kotlin and the Java Programming Language.
Reading through the comments here there's a lot of developers that are having great luck with Kotlin Extensions. That's great - and something we'll keep in mind as we look at ways to continue improving our APIs. If you haven't taken a look at Data Binding, definitely give it a shot.
As an aside, our internal code style guide is not intended to be directly applied outside of our codebase. For example, we use mPrefixVariables, but there's no reason that every app should follow that style.
澄清一下，直接访问视图和数据绑定是不同的。在 kotlin 之前，我们曾经有一个名为 butterknife 的库，它确实有助于直接访问视图。
所以回到 dataBinding，它所做的就是直接将值设置为视图/在 xml 中获取事件触发器（双向绑定）而不是你在 activity/fragment class.
中明确执行
有什么好处：假设您的布局中有 20 个 Textview xml，您希望将值设置为来自响应对象（具有 20 个对应字段）的那些 textview .
1)没有数据绑定，你需要访问每个视图并设置对象的值（所以20行代码）。
2) 使用数据绑定，您只需将对象绑定到 xml（一个衬里），您的 Xml 将使用 xml.[=10 中的绑定代码填充相应的字段=]
我想知道在开发 Android 应用程序时编写额外代码以在 Kotlin 中实现数据绑定的好处。 因为 Kotlin 扩展已经允许我们直接访问视图而不需要 findViewById。
我找到了答案here:
Hey! Developer Advocate for Android at Google here!
I wanted to add a bit of background here. Kotlin Extensions with synthetic views was never intentionally “recommended” though that shouldn’t be taken as a recommendation to not use them. If they're working for you please feel free to continue using them in your app!
We’ve been shifting away from them (e.g. we don’t teach them in the Udacity course) because they expose a global namespace of ids that’s unrelated to the layout that’s actually inflated with no checks against invalid lookups, are Kotlin only, and don't expose nullability when views are only present in some configuration. All together, these issues cause the API to increase number of crashes for Android apps.
On the other hand, they do offer a lightweight API that can help simplify view lookups. In this space it's also worth taking a look at Data Binding which also does automatic view lookups - as well as integrates with LiveData to automatically update your views as data changes.
Today, there's a few options in this space that work:
- Data Binding is the recommendation for view lookup as well as binding, but it does add a bit of overhead when compared to Android Kotlin Extensions. It's worth taking a look to see if this is a good fit for your app. Data Binding also allows you to observe LiveData to bind views automatically when data changes. Compared to Kotlin Extensions, it adds compile time checking of view lookups and type safety.
- Android Kotlin Extensions is not officially recommended (which is not the same as recommendation against). It does come with the issues mentioned above, so for our code we're not using them.
- Butter Knife is another solution that is extremely popular and works for both Kotlin and the Java Programming Language.
Reading through the comments here there's a lot of developers that are having great luck with Kotlin Extensions. That's great - and something we'll keep in mind as we look at ways to continue improving our APIs. If you haven't taken a look at Data Binding, definitely give it a shot.
As an aside, our internal code style guide is not intended to be directly applied outside of our codebase. For example, we use mPrefixVariables, but there's no reason that every app should follow that style.
澄清一下，直接访问视图和数据绑定是不同的。在 kotlin 之前，我们曾经有一个名为 butterknife 的库，它确实有助于直接访问视图。
所以回到 dataBinding，它所做的就是直接将值设置为视图/在 xml 中获取事件触发器（双向绑定）而不是你在 activity/fragment class.
中明确执行有什么好处：假设您的布局中有 20 个 Textview xml，您希望将值设置为来自响应对象（具有 20 个对应字段）的那些 textview .
1)没有数据绑定，你需要访问每个视图并设置对象的值（所以20行代码）。
2) 使用数据绑定，您只需将对象绑定到 xml（一个衬里），您的 Xml 将使用 xml.[=10 中的绑定代码填充相应的字段=]