我试图在一个带有cardview和firebase的片段中使用recyclerview（数据库中有所有的图像、名称和数量要传递到卡中），但我遇到了一个问题：
我的碎片里什么都没有！我的recyclerview不工作，我的卡不显示，我的碎片是空的，我的日志中没有错误。
以下是片段的java：

package com.example.progettocontab.assistenza;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.example.progettocontab.R;

import com.example.progettocontab.app.Articolo;
import com.example.progettocontab.app.ArticoloAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;
import com.google.firebase.database.FirebaseDatabase;

public class FragmentAssistenza extends Fragment {

    RecyclerView recyclerView;
    ArticoloAdapter adapter;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_assistenza, container, false);

        recyclerView = (RecyclerView) view.findViewById(R.id.recview);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity().getApplicationContext()));

        FirebaseRecyclerOptions<Articolo> options =
                new FirebaseRecyclerOptions.Builder<Articolo>()
                        .setQuery(FirebaseDatabase.getInstance().getReference().child("Articoli"), Articolo.class)
                        .build();

        adapter = new ArticoloAdapter(options);
        recyclerView.setAdapter(adapter);

        return view;
    }

    @Override
    public void onStart() {
        super.onStart();
        adapter.startListening();
    }

   @Override
    public void onStop() {
        super.onStop();
        adapter.stopListening();
    }
}

以下是片段的xml：

<?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=".assistenza.FragmentAssistenza">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginStart="1dp"
        android:layout_marginLeft="1dp"
        android:layout_marginTop="1dp"
        android:layout_marginEnd="1dp"
        android:layout_marginRight="1dp"
        android:layout_marginBottom="1dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

下面是适配器（带有viewholder类）：

package com.example.progettocontab.app;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import com.bumptech.glide.Glide;
import com.example.progettocontab.R;
import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;

public class ArticoloAdapter extends FirebaseRecyclerAdapter<Articolo, ArticoloAdapter.ViewHolder> {

    public ArticoloAdapter(@NonNull FirebaseRecyclerOptions<Articolo> options) {
        super(options);
    }

    @Override
    protected void onBindViewHolder(@NonNull ViewHolder holder, final int position, @NonNull Articolo model) {
        holder.nome.setText(model.getNome());
        holder.quantita.setText(model.getQuantita());
        Glide.with(holder.img.getContext()).load(model.getImg()).into(holder.img);

        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(v.getContext(), model.getNome(), Toast.LENGTH_SHORT).show();
            }
        });
    }

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

    class ViewHolder extends RecyclerView.ViewHolder {

        ImageView img;
        TextView nome;
        TextView quantita;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            img = (ImageView) itemView.findViewById(R.id.img);
            nome = (TextView) itemView.findViewById(R.id.nameText);
            quantita = (TextView) itemView.findViewById(R.id.amountText);
        }

    }

}

以下是阿替科洛的 java 语：

package com.example.progettocontab.app;

public class Articolo {

    private String nome;
    private String descrizione;
    private String quantita;
    private String img;
    private int ID;

    public Articolo(String nome, String descrizione, String quantita, String img, int ID) {
        this.nome = nome;
        this.descrizione = descrizione;
        this.quantita = quantita;
        this.img = img;
        this.ID = ID;
    }

    public String getNome() {
        return nome;
    }

    public void setNome(String nome) {
        this.nome = nome;
    }

    public String getDescrizione() {
        return descrizione;
    }

    public void setDescrizione(String descrizione) {
        this.descrizione = descrizione;
    }

    public String getQuantita() {
        return quantita;
    }

    public void setQuantita(String quantita) {
        this.quantita = quantita;
    }

    public String getImg() {
        return img;
    }

    public void setImg(String img) {
        this.img = img;
    }

    public int getID() {
        return ID;
    }

    public void setID(int ID) {
        this.ID = ID;
    }
}

以下是cardview的xml：

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    app:cardCornerRadius="5dp"
    android:elevation="5dp"
    app:cardUseCompatPadding="true">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:padding="15dp">

        <androidx.appcompat.widget.AppCompatImageView
            android:layout_width="80dp"
            android:layout_height="80dp"
            android:src="@mipmap/ic_launcher"
            android:layout_centerVertical="true"
            android:id="@+id/img"
            />

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/nameText"
            android:text="This is Demo Name"
            android:textStyle="bold"
            android:textSize="25sp"
            android:textColor="#000"
            android:layout_toRightOf="@id/img"
            android:layout_marginLeft="10dp"/>

        <TextView
            android:id="@+id/amountText"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/nameText"
            android:layout_marginLeft="6dp"
            android:layout_marginTop="12dp"
            android:layout_toRightOf="@id/img"
            android:text="This is Course Name"
            android:textColor="#000"
            android:textSize="25sp" />

    </RelativeLayout>

</androidx.cardview.widget.CardView>

尝试将recyclerview转换为onviewcreated，因为此时，fragment的视图会被填充，您可以访问recyclerview并将其膨胀。

@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
   View view = inflater.inflate(R.layout.fragment_assistenza, container, false);
   return view;
}

@Override
public void onViewCreated() {
   recyclerView = (RecyclerView) view.findViewById(R.id.recview);
   recyclerView.setLayoutManager(new LinearLayoutManager(getActivity().getApplicationContext()));

   FirebaseRecyclerOptions<Articolo> options =
                new FirebaseRecyclerOptions.Builder<Articolo>()
                        .setQuery(FirebaseDatabase.getInstance().getReference().child("Articoli"), Articolo.class)
                        .build();

   adapter = new ArticoloAdapter(options);
   recyclerView.setAdapter(adapter);
}

3条答案

按热度按时间

vx6bjr1n1#

试着移动 recyclerView.setAdapter(adapter) 在你之后 startListening 所以，把它从 onViewCreated() ，并将其添加到 onStart() ```
@Override
public void onStart() {
super.onStart();
adapter.startListening();
recyclerView.setAdapter(adapter);
}

赞(0）回复(0）举报 2021-06-29

pes8fvy92#

suzh9iv83#

我想你可能是因为 implementation 'com.google.firebase:firebase-messaging' 但是你还没有在你的清单中注册服务。因此，要么从gradle中删除该行（如果您不需要firebase的消息传递功能），要么将服务添加到清单中，如下所示：

<service
    android:name=".java.MyFirebaseMessagingService"
    android:exported="false">
    <intent-filter>
        <action android:name="com.google.firebase.MESSAGING_EVENT" />
    </intent-filter>
</service>

recyclerview与cardview和firebase的片段

3条答案

相关问题

热门标签

最新问答