如何使用绑定从 Fragment 访问 Activity 中的 BottomAppBar？

Question

由于 extention 已弃用，我已从 kotlin-extention 转移到绑定用法，因此我正在使用绑定重建整个应用程序。

我在从位于我的 Activity 中的片段访问 BottomAppBar 时遇到问题。

在绑定之前我使用的代码如下：

class CorpoFragment : Fragment() {
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        (activity as LetturaActivity).bottomAppBar.navigationIcon = ContextCompat.getDrawable(
            requireContext(),
            R.drawable.ic_baseline_menu_24
        )
     }
}

但现在我在该片段中设置了绑定，例如：

class CorpoFragment : Fragment() {

    private var fragmentCorpoBinding: FragmentCorpoBinding? = null
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        val binding = FragmentCorpoBinding.inflate(inflater, container, false)
        fragmentCorpoBinding = binding
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        // how can i access the bottomAppBar from the activity at this point?
    }

删除 kotlin 扩展后，我在第一个代码块上得到 Unresolved reference: bottomAppBar..

Answer 1

可通过 binding class.

访问变量

private lateinit var binding: FragmentCorpoBinding

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
    binding = FragmentCorpoBinding.inflate(inflater, container, false)
    return binding.root
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    binding.bottomAppBar
}

我建议你不要访问从 Fragment 到 Activity 的视图元素，因为每个 activity/fragment 都应该有其独立的视图（关注点分离）。如果您确实需要它，只需在 Activity:

中添加类似的内容

class LetturaActivity {

 fun updateBottomMenu() {
  binding.bottomAppBar.navigationIcon = ContextCompat.getDrawable(
            requireContext(),
            R.drawable.ic_baseline_menu_24
        )
 }

}

如何使用绑定从 Fragment 访问 Activity 中的 BottomAppBar？

How to use bindings to access BottomAppBar in Activity from Fragment?

android

kotlin

android-databinding