Android中ViewAllFragment重开时GridView列表数据重复问题求助

问题描述 #

关闭ViewAllFragment并重新打开后，GridView中的列表会反复加载相同数据，导致内容重复。已尝试在Fragment销毁时清空Adapter列表、仅当Adapter为空时提交数据，但未解决问题。

相关代码 #

XML布局

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.view_all.ViewAllFragment">


    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone"
        android:background="@color/lightGray"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <GridView
        android:id="@+id/gridView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/lightGray"
        android:verticalSpacing="1dp"
        android:horizontalSpacing="1dp"
        android:visibility="gone"
        tools:visibility="visible"
        android:numColumns="auto_fit"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

GridProductAdapter代码

class GridProductAdapter : BaseAdapter() {

    private var productScrollModelList = arrayListOf<HorizontalProductScrollModel>()

    fun submitList(productScrollModelList: List<HorizontalProductScrollModel> ){
        this.productScrollModelList.addAll(productScrollModelList)
        notifyDataSetChanged()

        Log.d(TAG, "submitList: size ${productScrollModelList.size}")
    }

    fun clearList(){
        this.productScrollModelList.clear()
        notifyDataSetChanged()
    }

    override fun getCount(): Int {
        return productScrollModelList.size
    }

    override fun getItem(i: Int): Any? {
        return null
    }


    override fun getItemId(i: Int): Long {
        return 0
    }

    override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {

        var localConvertView: View? = convertView

        val binding: HorizontalScrollItemLayoutBinding

        if (localConvertView == null) {
            binding = HorizontalScrollItemLayoutBinding.inflate(
                LayoutInflater.from(parent.context)
            )
            localConvertView = binding.root
            localConvertView.setTag(R.id.viewBinding, binding)
        } else {
            binding = localConvertView.getTag(R.id.viewBinding) as HorizontalScrollItemLayoutBinding
        }

        Glide.with(binding.root.context)
            .load(productScrollModelList[position].productImage)
            .placeholder(R.drawable.placeholder_image)
            .into(binding.hsProductImage)
        binding.hsProductName.text = productScrollModelList[position].productName
        binding.hsProductDescription.text = productScrollModelList[position].productDescription
        binding.hsProductPrice.text = "Rs.${productScrollModelList[position].productPrice}/-"

        return localConvertView
    }
}

ViewAllFragment代码

private var _binding: FragmentViewAllBinding? = null
private val binding get() = _binding!!

private val LAYOUT_CODE = 0
private val wishList= arrayListOf<WishListModel>()

private val wishlistAdapter = WishlistAdapter(false)

private val args by navArgs<ViewAllFragmentArgs>()

private var layoutCode:Int =0

private val gridProductAdapter by lazy { GridProductAdapter()  }

override fun onCreateView(
    inflater: LayoutInflater,
    container: ViewGroup?,
    savedInstanceState: Bundle?
): View {
    _binding = FragmentViewAllBinding.inflate(inflater)

    layoutCode = args.layoutCode
    (requireActivity() as MainActivity).fragmentTitleAndActionBar(args.title)

    return binding.root
}

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

    if(layoutCode == 0) {
        wishList.addAll(args.viewAllProductList!!)
        wishlistAdapter.asyncListDiffer.submitList(wishList)
        binding.recyclerView.apply {
            visibility = View.VISIBLE
            layoutManager = LinearLayoutManager(requireContext(),LinearLayoutManager.VERTICAL,false)
            adapter = wishlistAdapter
        }
    }else if(layoutCode == 1) {
        binding.gridView.visibility = View.VISIBLE
        binding.gridView.adapter = gridProductAdapter

        Log.d(TAG, "onViewCreated: horizontalProductScrollModelList size ${args.horizontalProductScrollModelList.size}")

        if(gridProductAdapter.isEmpty) {
            gridProductAdapter.submitList(args.horizontalProductScrollModelList.toList())
        }
    }
}

override fun onDestroyView() {
    super.onDestroyView()
    gridProductAdapter.clearList()
    _binding = null
}

问题根源及解决方案 #

1. Adapter提交数据逻辑错误 #

GridProductAdapter的submitList方法使用addAll追加数据，而非替换原有数据，导致每次调用都会重复添加相同内容。

修复代码：
修改submitList方法，先清空原有列表再添加新数据：

fun submitList(productScrollModelList: List<HorizontalProductScrollModel> ){
    this.productScrollModelList.clear()
    this.productScrollModelList.addAll(productScrollModelList)
    notifyDataSetChanged()
    Log.d(TAG, "submitList: size ${productScrollModelList.size}")
}

2. 空列表判断无效 #

ViewAllFragment中使用gridProductAdapter.isEmpty判断，但GridProductAdapter未定义该属性，导致判断逻辑不生效，每次都会执行submitList。

修复代码：
在GridProductAdapter中添加isEmpty属性：

val isEmpty: Boolean
    get() = productScrollModelList.isEmpty()

或直接在Fragment中用gridProductAdapter.count == 0替代判断条件。

3. Fragment生命周期适配 #

若Fragment是通过hide/show方式管理而非replace，onDestroyView不会被调用，导致clearList无法执行。此时可在onViewCreated中先清空列表再提交数据，无需判断：

else if(layoutCode == 1) {
    binding.gridView.visibility = View.VISIBLE
    binding.gridView.adapter = gridProductAdapter

    Log.d(TAG, "onViewCreated: horizontalProductScrollModelList size ${args.horizontalProductScrollModelList.size}")

    gridProductAdapter.clearList() // 先清空
    gridProductAdapter.submitList(args.horizontalProductScrollModelList.toList())
}

内容的提问来源于stack exchange，提问作者Dr Mido