从其他适配器更新 recyclerview 适配器

Question

我想要的 - 我有类别 recyclerview 和 quoteList recyclerview。当用户点击任何类别时，它应该 display/animate 该类别的报价。

问题 - 1. 现在我已经尝试设置从类别适配器到我的报价适配器的列表但是它给了我空指针异常。 2. 我已经实现了 DiffUtils，但同样它不会更新数据而是 return 空指针。

问题 - 我如何更新类别 OnBindViewHolder 中的引用 Recyclerview？

这是代码...

类别适配器

public class category_adapter extends RecyclerView.Adapter<category_ViewHolder>{

private ArrayList<CategoryModel> categoryList;

public category_adapter(ArrayList<CategoryModel> categoryList) {
    this.categoryList = categoryList;
}

@NonNull
@Override
public category_ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.category_recyclerview, parent, false);
    return new category_ViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull category_ViewHolder holder, int position) {

    ArrayList<FirebaseModel> quoteList = new ArrayList<>();
    TextView item = holder.item;
    item.setText(categoryList.get(position).getCategoryName());

    holder.categoryLayout.setOnClickListener(v -> {
        FirebaseFirestore db = FirebaseFirestore.getInstance();

        Query first = db.collection("quotes")
                .whereGreaterThanOrEqualTo("Tag",categoryList.get(position).getCategoryName())
                .orderBy("Tag")
                .limit(10);

        first.get()
            .addOnCompleteListener(task -> {
                if (task.isSuccessful()) {
                    for (QueryDocumentSnapshot document : Objects.requireNonNull(task.getResult())) {

                        quoteList.add(new FirebaseModel(
                                document.getData().get("id").toString(),
                                document.getData().get("Quote").toString(),
                                document.getData().get("Author").toString(),
                                Integer.parseInt(document.getData().get("Likes").toString()),
                                document.getData().get("Tag").toString())
                        );
                        new MainActivity().setQupteAdapter(quoteList);

                    }
                } else {
                    Log.d("FIRESTORE", "Error getting documents: ", task.getException());
                }
            });
    });
}

    @Override
    public int getItemCount() {
        return categoryList.size();
    }
}

new MainActivity().setQupteAdapter(quoteList);

在上面的代码中，我尝试制作适配器 public 并用于更新适配器。但不工作，同样我尝试使用方法设置。:(不工作..

引用适配器

public class quoteAdapter extends RecyclerView.Adapter<quoteViewHolder>{

ArrayList<FirebaseModel> quoteList;

public void setList(ArrayList<FirebaseModel> newList) {
    ArrayList<FirebaseModel> oldList = this.quoteList;
    DiffUtil.DiffResult diffResult = DiffUtil.calculateDiff(new quoteAdapterDiffUtil(newList, oldList), true);
    this.quoteList = newList;
    diffResult.dispatchUpdatesTo(this);
}

public quoteAdapter(ArrayList<FirebaseModel> quoteList) {
    this.quoteList = quoteList;
}

@NonNull
@Override
public quoteViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.quote_recycler_item, parent, false);
    return new quoteViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull final quoteViewHolder holder, final int position) {
    holder.autherName.setText("- " + quoteList.get(position).getAuthor());
    holder.quote.setText(quoteList.get(position).getQuote());
}

    @Override
    public int getItemCount() {
        return quoteList.size();
    }
}

帮我想办法更新报价单recyclerview。

Answer 1

我的实现方式是：

为每个 RecyclerView 实现项目点击监听器

如何实现项目点击侦听器以便 Activity/Fragment 可以在从 RecyclerView 收到事件时采取行动：Click Here

现在两个 RecyclerView 都有一个项目点击侦听器，Shared Activity/Fragment 可以采取行动：

Activity/Fragment:

@Override
public void onCategoryItemClickListener(int position) {
    //updateItem() is a function inside your adapter that updates data at 
    //the specified index
    quoteAdapter.updateItem(position, newData)
    quoteAdapter.notifyItemChanged(position)
}

//implement the same for onQuoteItemClickListener

Answer 2

以下内容将使您的代码只需少量更改即可工作

创建界面

interface QuoteUpdate {
    void updateAdapter(ArrayList<FirebaseModel> quoteList);
}

在category_adapter

private ArrayList<CategoryModel> categoryList;
private QuoteUpdate quoteUpdate;

public category_adapter(ArrayList<CategoryModel> categoryList, QuoteUpdate quoteUpdate) {
    this.categoryList = categoryList;
    this.quoteUpdate = quoteUpdate;
}

//..

将MainActivity().setQupteAdapter(quoteList);替换为quoteUpdate.update(quoteList);

在MainActivity

category_adapter adapter = new category_adapter(categoryList, new QuoteUpdate {
    @Override
    public void updateAdapter(ArrayList<FirebaseModel> quoteList) {
        setQupteAdapter(quoteList);
    }
});

从其他适配器更新 recyclerview 适配器

Update recyclerview adapter from other adapter

android

adapter

android-recyclerview

android-diffutils