如何在单个Activity中使用双ViewBinding并修复BottomSheet异常

你当前的代码存在重复添加BottomSheet布局的问题：

• activity_main.xml已经通过<include>标签引入了item_bottom_sheet布局
• 但在MainActivity里又通过ItemBottomSheetBinding.inflate(..., binding.root, true)手动将该布局再次添加到CoordinatorLayout中
  这会导致界面上存在两个BottomSheet实例，BottomSheetBehavior控制的是手动添加的那个，而include的实例也会占用布局空间，最终引发显示异常。

步骤1：给include标签添加id #

修改activity_main.xml中的include标签，增加唯一id，方便通过ViewBinding获取绑定实例：

<include
    android:id="@+id/bottom_sheet_include"
    layout="@layout/item_bottom_sheet" />

步骤2：修改MainActivity代码，复用已include的布局绑定 #

删除手动inflateItemBottomSheetBinding的代码，改用bind()方法获取已存在于布局树中的BottomSheet绑定：

class MainActivity : AppCompatActivity() {
    private lateinit var binding : ActivityMainBinding
    private lateinit var bottomSheetBinding: ItemBottomSheetBinding
    private lateinit var bottomSheetBehavior: BottomSheetBehavior<*>
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(LayoutInflater.from(this))
        setContentView(binding.root)

        // 绑定已通过include引入的BottomSheet布局
        bottomSheetBinding = ItemBottomSheetBinding.bind(binding.bottomSheetInclude.root)

        bottomSheetBehavior = BottomSheetBehavior.from(bottomSheetBinding.bottomSheet)

        bottomSheetBehavior.peekHeight = 0
        bottomSheetBehavior.state = BottomSheetBehavior.STATE_COLLAPSED

        binding.expand.setOnClickListener {
            bottomSheetBehavior.state = BottomSheetBehavior.STATE_EXPANDED
        }

        binding.collapse.setOnClickListener {
            bottomSheetBehavior.state = BottomSheetBehavior.STATE_COLLAPSED
        }

        bottomSheetBinding.btnCancel.setOnClickListener {
            Toast.makeText(this, "xczc", Toast.LENGTH_SHORT).show()
        }
    }
}

原理说明 #

• ItemBottomSheetBinding.bind(view)方法会复用布局树中已存在的View实例生成绑定对象，不会重复创建和添加View
• 这样BottomSheetBehavior就会绑定到<include>引入的那个唯一BottomSheet实例上，和用findViewById的逻辑一致，从而恢复正常的展开/收起行为

内容的提问来源于stack exchange，提问作者Super Hoang