Question

我想使用recyclerview在我的应用程序屏幕上显示firebase数据。我的应用程序正在运行，没有任何错误，但数据未显示在屏幕上。请帮忙这是我的代码：请检查并帮助我使用recyclerview

显示从firebase到应用程序屏幕的数据

VenuesActivity.java

Grouping everything and then filtering

venuesactivity.xml

package com.cornicore.icccricketworldcup2019;

import android.content.Context;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;

import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.squareup.picasso.Picasso;

public class VenuesActivity extends AppCompatActivity {

    private RecyclerView mBlogList;
    private DatabaseReference mDatabase;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_venues);


        mDatabase = FirebaseDatabase.getInstance().getReference().child("Venues");
        mDatabase.keepSynced(true);
        mBlogList = (RecyclerView) findViewById(R.id.myrecyclerview);
        mBlogList.setHasFixedSize(true);
        mBlogList.setLayoutManager(new LinearLayoutManager(this));



    }

    FirebaseRecyclerOptions<Blog> options =
            new FirebaseRecyclerOptions.Builder<Blog>()
                    .setQuery(mDatabase, Blog.class)
                    .build();

    @Override
    protected void onStart() {
        super.onStart();



        FirebaseRecyclerAdapter adapter = new FirebaseRecyclerAdapter<Blog, BlogViewHolder>(options) {
            @Override
            public BlogViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
                View view = LayoutInflater.from(parent.getContext())
                        .inflate(R.layout.venue_row, parent, false);

                return new BlogViewHolder(view);
            }

            @Override
            protected void onBindViewHolder(BlogViewHolder holder, int position, Blog model) {
                // Bind the image_details object to the BlogViewHolder
                // ...

                holder.setTitle(model.getTitle());
                holder.setDesc(model.getDesc());
                holder.setImage(getApplicationContext(),model.getImage());

            }
        };




//        FirebaseRecyclerAdapter<Blog,BlogViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Blog, BlogViewHolder>
//                (Blog.class,R.layout.venue_row,BlogViewHolder.class,mDatabase) {
//            @Override
//            protected void onBindViewHolder(@NonNull BlogViewHolder viewHolder, int position, @NonNull Blog model) {
//
//                viewHolder.setTitle(model.getTitle());
//                viewHolder.setDesc(model.getDesc());
//                viewHolder.setImage(getApplicationContext(),model.getImage());
//
//            }
//
//            @NonNull
//            @Override
//            public BlogViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
//                return null;
//            }
//        };

        mBlogList.setAdapter(adapter);

    }

    public static class BlogViewHolder extends RecyclerView.ViewHolder{
        View mView;
        public BlogViewHolder(View itemView){
            super(itemView);
            mView = itemView;
        }
        public void setTitle(String title){
            TextView post_title = (TextView) mView.findViewById(R.id.post_title);
            post_title.setText(title);
        }
        public void setDesc(String desc){
            TextView post_desc = (TextView) mView.findViewById(R.id.post_desc);
            post_desc.setText(desc);
        }
        public void setImage(Context ctx, String image){
            ImageView post_Image = (ImageView) mView.findViewById(R.id.post_image);
            Picasso.with(ctx).load(image).into(post_Image);
        }
    }

}

Blog.java

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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=".VenuesActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/myrecyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </android.support.v7.widget.RecyclerView>

</RelativeLayout>

venue_row.xml

package com.cornicore.icccricketworldcup2019;

public class Blog {

    private String title;
    private String desc;
    private String image;

    public Blog(String title, String desc, String image) {
        this.title = title;
        this.desc = desc;
        this.image = image;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }

    public String getImage() {
        return image;
    }

    public void setImage(String image) {
        this.image = image;
    }


    public Blog(){

    }

}

build.gradel

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.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"
    android:orientation="vertical"
    android:layout_margin="7dp"
    app:cardCornerRadius="12dp"
    android:elevation="90dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="248dp"
        android:orientation="vertical"
        android:background="#121111">

        <ImageView
            android:id="@+id/post_image"
            android:layout_width="match_parent"
            android:layout_height="180dp"
            android:scaleType="centerCrop"/>

        <TextView
            android:id="@+id/post_title"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:textSize="20dp"
            android:text="POST TITLE"
            android:textColor="#fff"/>

        <TextView
            android:id="@+id/post_desc"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="POST DESC"
            android:textColor="#fff"/>


    </LinearLayout>



</android.support.v7.widget.CardView>

Answer 1

解决这个问题，请按照以下步骤进行：

删除：mBlogList.setHasFixedSize(true);
在adapter方法中移动onCreate()的声明。

制作adapter可变全球：

private FirebaseRecyclerAdapter<Blog, BlogViewHolder> adapter;

从FirebaseRecyclerAdapter<Blog, BlogViewHolder>方法移除onCreate()。

在onStart()和onStop()方法中添加以下代码行。

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

@Override
protected void onStop() {
    super.onStop();
    if(adapter != null) {
        adapter.stopListening();
    }
}

Answer 2

我认为你必须编写错误的代码。你可以尝试这种方式。

    public class SavedRestaurantListActivity extends AppCompatActivity {
        private DatabaseReference mRestaurantReference;
        private FirebaseRecyclerAdapter mFirebaseAdapter;

        @Bind(R.id.recyclerView) RecyclerView mRecyclerView;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            setContentView(R.layout.activity_restaurants);
            ButterKnife.bind(this);

            mRestaurantReference = FirebaseDatabase.getInstance().getReference(Constants.FIREBASE_CHILD_RESTAURANTS);
            setUpFirebaseAdapter();
        }

        private void setUpFirebaseAdapter() {
            mFirebaseAdapter = new FirebaseRecyclerAdapter<Restaurant, FirebaseRestaurantViewHolder>
                    (Restaurant.class, R.layout.restaurant_list_item, FirebaseRestaurantViewHolder.class, 
                        mRestaurantReference) {

                @Override
                protected void populateViewHolder(FirebaseRestaurantViewHolder viewHolder, 
                    Restaurant model, int position) {
                    viewHolder.bindRestaurant(model);
                }
            };
            mRecyclerView.setHasFixedSize(true);
            mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
            mRecyclerView.setAdapter(mFirebaseAdapter);
        }

        @Override
        protected void onDestroy() {
            super.onDestroy();
            mFirebaseAdapter.cleanup();
        }
        @Override
        protected void onStart() {
            super.onStart();
            mFirebaseAdapter.startListening();
        }

        @Override
        protected void onStop() {
            super.onStop();
            if(mFirebaseAdapter != null) {
                mFirebaseAdapter.stopListening();
            }
        }
    }

Answer 3

解决方案很简单。请将回收站视图的layout_height从match_parent更改为wrap_content

稍后谢谢

Answer 4

在设置apdapter之后添加以下行：

mBlogList.setAdapter(adapter);
mFirebaseAdapter.startListening();

RecyclerView未在我的应用屏幕上显示来自Firebase的数据

4 个答案: