RecyclerView Adapter无方法执行：Fragment迁移后列表不显示

核心问题 #

你的Fragment存在视图绑定实例不匹配的问题：

• 在onCreateView中手动inflate布局并返回了一个视图实例
• 但在onViewCreated里又通过PlacnikiFragmentBinding.inflate(layoutInflater)创建了全新的Binding对象，这个Binding对应的视图根本没有被添加到Fragment的视图层级中
• 你给新Binding里的RecyclerView设置了Adapter，但界面上实际显示的是onCreateView返回的那个未设置Adapter的RecyclerView，所以Adapter的方法完全不会被调用

修正方案（二选一） #

方案1：在onCreateView中初始化Binding

class PlacnikiFragment : Fragment() {

    private val TAG = "PlacnikiFragment"
    private lateinit var binding: PlacnikiFragmentBinding
    lateinit var viewModel: MainViewModel
    private val retrofitService = RetrofitService.getInstance()

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // 直接通过Binding初始化布局并返回根视图
        binding = PlacnikiFragmentBinding.inflate(inflater, container, false)
        return binding.root
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        // 无需重新创建Binding，直接使用已初始化的实例
        viewModel = ViewModelProvider(this, ViewModelFactory(Repository(retrofitService))).get(
            MainViewModel::class.java
        )

        viewModel.placnikiList.observe(viewLifecycleOwner, {
            Log.d(TAG, "placnikiList: $it")
            binding.recyclerview.adapter = PlacnikiAdapter(it)
            // 必须设置LayoutManager（XML中没设置的话，代码里一定要加）
            binding.recyclerview.layoutManager = LinearLayoutManager(requireContext())
        })
        viewModel.errorMessage.observe(viewLifecycleOwner, {
            Log.d(TAG, "errorMessage: $it")
        })
        viewModel.getVsiPlacniki()
    }
}

方案2：通过已有视图绑定Binding

class PlacnikiFragment : Fragment() {

    private val TAG = "PlacnikiFragment"
    private lateinit var binding: PlacnikiFragmentBinding
    lateinit var viewModel: MainViewModel
    private val retrofitService = RetrofitService.getInstance()

    override fun onCreateView(
        inflater: LayoutInflater,
        container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.placniki_fragment, container, false)
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        // 使用Fragment已加载的视图创建Binding，而不是重新inflate
        binding = PlacnikiFragmentBinding.bind(view)
        
        viewModel = ViewModelProvider(this, ViewModelFactory(Repository(retrofitService))).get(
            MainViewModel::class.java
        )

        viewModel.placnikiList.observe(viewLifecycleOwner, {
            Log.d(TAG, "placnikiList: $it")
            binding.recyclerview.adapter = PlacnikiAdapter(it)
            // 必须设置LayoutManager（XML中没设置的话，代码里一定要加）
            binding.recyclerview.layoutManager = LinearLayoutManager(requireContext())
        })
        viewModel.errorMessage.observe(viewLifecycleOwner, {
            Log.d(TAG, "errorMessage: $it")
        })
        viewModel.getVsiPlacniki()
    }
}

额外注意事项 #

• 必须设置LayoutManager：RecyclerView如果没有LayoutManager（不管是XML中配置还是代码中设置），无法计算条目布局，即使Adapter设置正确也不会显示内容
• 可以在Adapter的getItemCount方法中添加日志，验证该方法是否被调用，确认问题是否解决

内容的提问来源于stack exchange，提问作者Jure R