當我使用recylceviewTextView從firebase中檢索孩子時，不會顯示

當我運行我的應用程式并添加或顯示 RecycleView 串列時，我正在使用 Android Studio，文本視圖僅顯示標題而不是 firebase 內的資料這是 textview addCateogryclass 會導致這種情況的原因是什么？在 firebase child 上使用了相同的資料。

firebase 實時資料庫 Firebase

模型類別類

public class ModelCategoryClass {
    //same variable in db
    String id, category, uid;
    long timestamp;

    public ModelCategoryClass() {}

    public ModelCategoryClass(String id, String category, String uid, long timestamp) {
        this.id = id;
        this.category = category;
        this.uid = uid;
        this.timestamp = timestamp;
    }


    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getCategory() {
        return category;
    }

    public void setCategory(String category) {
        this.category = category;
    }

    public String getUid() {
        return uid;
    }

    public void setUid(String uid) {
        this.uid = uid;
    }

    public long getTimestamp() {
        return timestamp;
    }

    public void setTimestamp(long timestamp) {
        this.timestamp = timestamp;
    }
}

配接器類別類

public class AdapterCategoryClass extends RecyclerView.Adapter<AdapterCategoryClass.HolderCategory> {

    private Context context;
    private ArrayList<ModelCategoryClass> categoryClassArrayList;
    //xml rows_categorys
    private RowsCategorysBinding binding;




    //constucor
    public AdapterCategoryClass(Context context, ArrayList<ModelCategoryClass> categoryClassArrayList) {
        this.context = context;
        this.categoryClassArrayList = categoryClassArrayList;
    }





    ///////////////
    //generated from RecyclerView.Adapter<AdapterCategoryClass.HolderCategory>
    @NonNull
    @Override
    public HolderCategory onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        //binding

        binding = RowsCategorysBinding.inflate(LayoutInflater.from(context), parent, false);
        return new HolderCategory(binding.getRoot());
        //return new HolderCategory(RowsCategorysBinding.inflate(LayoutInflater.from(parent.getContext()),parent,false));
    }


    //getting data
    @Override
    public void onBindViewHolder(@NonNull HolderCategory holder, int position) {
        ModelCategoryClass model = categoryClassArrayList.get(position);

        String id = model.getId();
        String category = model.getId();
        String uid = model.getId();
        long timestamp = model.getTimestamp();


//remove btn
        //as we declred remove btn in HolderCatogory method
        holder.removeBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(context,"" category,Toast.LENGTH_SHORT).show();



            }
        });

    }

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







    //hold lists xml
    public class HolderCategory extends RecyclerView.ViewHolder {
        TextView textViewListCatt;
        ImageButton removeBtn;



        //constu
        public HolderCategory(@NonNull View itemView) {
            super(itemView);

            textViewListCatt = binding.textViewListCat;
            removeBtn = binding.removeBtn;

        }
    }



}

CategoryAddActivity 類

    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = ActivityCategoryAddBinding.inflate(getLayoutInflater());
        setContentView(binding.getRoot());
//init firebase auth
        firebaseAuth = FirebaseAuth.getInstance();

        ShowCategories();
    private void ShowCategories() {

        categoryClassArrayList = new ArrayList<>();
        DatabaseReference ref = FirebaseDatabase.getInstance().getReference("Categories");


        ref.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
//clear array befor add data
                categoryClassArrayList.clear();
                for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
                    //get data from child in database
                    ModelCategoryClass mod = dataSnapshot.getValue(ModelCategoryClass.class);
                    //add data to array
                    categoryClassArrayList.add(mod);
                }
                //start using adapter
                adapterCategoryClass = new AdapterCategoryClass(CategoryAddActivity.this, categoryClassArrayList);
                //get recycleListview rom xml and set it with defualt set method
                binding.recycleList.setAdapter(adapterCategoryClass);

            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {

            }
        });


    }

uj5u.com熱心網友回復：

以下代碼行：

ModelCategoryClass model = categoryClassArrayList.get(position);
String id = model.getId();
String category = model.getId();
String uid = model.getId();
long timestamp = model.getTimestamp();

應改為：

ModelCategoryClass model = categoryClassArrayList.get(position);
String id = model.getId();
String category = model.getCategory(); //??
String uid = model.getUid(); //??
long timestamp = model.getTimestamp();

這意味著您需要呼叫相應的getter。但這不是問題的全部。您沒有顯示某些內容，因為您沒有將這些值設定為相應的視圖。為了解決這個問題，您必須在 HolderCategory 類中創建一個將資料實際系結到視圖的方法。例如，要設定類別，您應該使用如下內容：

void setCategory(String category) {
    binding.textViewListCat.setText(category);
}

然后從你的 onBindViewHolder 方法內部呼叫這個方法，如下所示：

holder.setCategory(category);

標籤：爪哇 安卓 火力基地 谷歌云平台 firebase-实时数据库

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