Android在recycleview片段选项卡布局消息中填充Firebase数据：E / RecyclerView：未连接适配器；跳过布局

Question

我是android firebase的新手。我的问题是我想在数据库中显示我的数据列表 recycleview。我有一个包含3个选项卡的布局。我要在其中显示数据的第一个标签中 在其中遇到了回收站视图，我也是方法

  

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addValueEventListener

  

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获取Firebase数据。每当我启动该应用程序时，它什么都不会显示

  

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E / RecyclerView：未连接适配器；跳过布局

  

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。有人可以帮助我吗？在此先感谢

我的Firebase数据 [1]：https://imgur.com/gallery/uIOEPuA

HomeActivity.java

 package com.example.saincurin.htfacile;

import android.os.Build;
import android.support.design.widget.NavigationView;
import android.support.design.widget.TabItem;
import android.support.design.widget.TabLayout;
import android.support.v4.content.ContextCompat;
import android.support.v4.view.GravityCompat;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

import com.example.saincurin.htfacile.Adapters.PageAdapter;

public class HomeActivity extends AppCompatActivity {

    private Toolbar toolbar;
    TabLayout tabLayout;
    ViewPager viewPager;
    private DrawerLayout mDrawer;
    private NavigationView nvDrawer;
    private ActionBarDrawerToggle drawerToggle;


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

        toolbar = findViewById(R.id.toolbar);
        mDrawer = findViewById(R.id.drawer_layout);
        nvDrawer = findViewById(R.id.nvView);
        tabLayout = findViewById(R.id.tabLayout);
        viewPager = findViewById(R.id.viewPager);

        toolbar.setTitle(getResources().getString(R.string.app_name));
        setSupportActionBar(toolbar);
        // Set up Drawer View



        PagerAdapter pagerAdapter = new PageAdapter(getSupportFragmentManager(), HomeActivity.this);
        viewPager.setAdapter(pagerAdapter);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            getWindow().setStatusBarColor(ContextCompat.getColor(HomeActivity.this,
                    R.color.colorAccent));
        }

        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this, mDrawer, toolbar,
                R.string.drawer_open, R.string.drawer_close);
        mDrawer.addDrawerListener(toggle);
        toggle.syncState();

        // give the Tablayout the viewPager
        tabLayout.setupWithViewPager(viewPager);
//        setupDrawerContent(nvDrawer);
    }

    @Override
    public void onBackPressed() {
        if (mDrawer.isDrawerOpen(GravityCompat.START)) {
            mDrawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    //    private void setupDrawerContent(NavigationView navigationView) {
//        navigationView.setNavigationItemSelectedListener(
//                new NavigationView.OnNavigationItemSelectedListener() {
//                    @Override
//                    public boolean onNavigationItemSelected(MenuItem menuItem) {
//                        selectDrawerItem(menuItem);
//                        return true;
//                    }
//                });
//    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_products, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == R.id.action_more) {
            Toast.makeText(this, "The more is selected", Toast.LENGTH_SHORT).show();
        }else if (item.getItemId() == R.id.action_search) {
            Toast.makeText(this, "The search is selected", Toast.LENGTH_SHORT ).show();
        }else if (item.getItemId() == R.id.drawer_layout) {
            mDrawer.openDrawer(GravityCompat.START);
        }
        return true;
    }
}

我的模型

package com.example.saincurin.htfacile.ModelData;

public class DataModel {

    private String  description;
    private String name;
    private String image;
    private String price;
    private String quantity;


    //constructor
    public DataModel() {

    }

    public DataModel(String name, /*String description,*/ String image, String price) {
        this.name = name;
//        this.description = description;
        this.image = image;
        this.price = price;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getImage() {
        return image;
    }

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

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getQuantity() {
        return quantity;
    }

    public void setQuantity(String quantity) {
        this.quantity = quantity;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }
}

我的适配器

package com.example.saincurin.htfacile.Adapters;

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.saincurin.htfacile.ModelData.DataModel;
import com.example.saincurin.htfacile.R;
import com.squareup.picasso.Picasso;

import java.util.List;


// Create the basic adapter extending from RecyclerView.Adapter
// Note that we specify the custom ViewHolder which gives us access to our views

public class ProductsAdapter extends RecyclerView.Adapter<ProductsAdapter.ProductsviewHolder> {
    private Context mcontext;
    // Store a member variable for the contacts
    private List<DataModel> mDataModel;

    public ProductsAdapter(Context context, List<DataModel> mDataModel) {
        mcontext = context;
        this.mDataModel = mDataModel;
    }


    // Usually involves inflating a layout from XML and returning the holder
    @NonNull
    @Override
    public ProductsviewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        //inflate the custom Layout
        View dataView = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_row, parent, false);

        //return a new holder instance
        return new  ProductsviewHolder(dataView);


    }

    // Involves populating data into the item through holder
    @Override
    public void onBindViewHolder(@NonNull ProductsviewHolder holder, int position) {
        // Get the data model based on position
        DataModel dataModel = mDataModel.get(position);

        // Set item views based on your views and data model
        holder.txtName.setText(dataModel.getName());
//        holder.txtDescription.setText(dataModel.getDescription());
        holder.txtPrice.setText(dataModel.getPrice());
        Picasso.with(mcontext)
                .load(dataModel.getImage())
                .fit()
                .centerCrop()
                .into(holder.imageView);

    }

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

    // Provide a direct reference to each of the views within a data item
    // Used to cache the views within the item layout for fast access
    public class ProductsviewHolder extends RecyclerView.ViewHolder {
        public TextView txtName;
//        public TextView txtDescription;
        public TextView txtPrice;
        public TextView txtQuantity;
        public ImageView imageView;


        // We also create a constructor that accepts the entire item row
        // and does the view lookups to find each subview
        public ProductsviewHolder(View itemView) {

            // Stores the itemView in a public final member variable that can be used
            // to access the context from any ViewHolder instance.
            super(itemView);

            txtName = itemView.findViewById(R.id.rvTitleTv);
//            txtDescription = itemView.findViewById(R.id.rDescriptionTv);
            txtPrice = itemView.findViewById(R.id.rPrice);
            imageView = itemView.findViewById(R.id.rImageView);

        }
    }


}

我的第一个“片段”标签

package com.example.saincurin.htfacile.fragments;


import android.content.Context;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

import com.example.saincurin.htfacile.Adapters.ProductsAdapter;
import com.example.saincurin.htfacile.ModelData.DataModel;
import com.example.saincurin.htfacile.R;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;

import java.util.ArrayList;
import java.util.List;

/**
 * A simple {@link Fragment} subclass.
 */
public class ProductsFragment extends Fragment {

    private RecyclerView mRecycleView;
    private ProductsAdapter mProductsAdapter;

    private DatabaseReference mReference;
    private List<DataModel> mDataModel;

    View v;

    public ProductsFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, final ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        v = inflater.inflate(R.layout.fragment_products, container, false);

        //RecycleView
        mRecycleView = v.findViewById(R.id.recycleView);
        mRecycleView.setHasFixedSize(true);
        //set Layout as LinearLayout
        mRecycleView.setLayoutManager(new LinearLayoutManager(getContext()));

        mDataModel = new ArrayList<>();


        //send Query FirebaseDatabase
       mReference = FirebaseDatabase.getInstance().getReference("uploads");

        Log.e("DEBUG", "The Reference :"+mReference);

        mReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                    DataModel dataModel = postSnapshot.getValue(DataModel.class);
                    mDataModel.add(dataModel);
                }
//                Log.e("DEBUG","The data model "+ mDataModel.toString());
                mProductsAdapter = new ProductsAdapter(getContext(), mDataModel);
//                Log.e("DEBUG","The data model "+ mProductsAdapter);

                //set the adapter to the recyclerview
                mRecycleView.setAdapter(mProductsAdapter);
                mProductsAdapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
                Toast.makeText(getContext(), databaseError.getMessage(), Toast.LENGTH_LONG).show();
            }
        });


        return v;
    }

}

我的第一个标签页传呼机的布局

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".fragments.ProductsFragment">

    <!--RecycleView-->
    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycleView"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</FrameLayout>

HomeActivity的布局

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout 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:id="@+id/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context=".HomeActivity"
    tools:openDrawer="start">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/colorPrimary"
            android:minHeight="?attr/actionBarSize"
            android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:theme="@style/ThemeOverlay.AppCompat.Dark" />

        <android.support.design.widget.TabLayout
            android:id="@+id/tabLayout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_below="@id/toolbar"
            style="@style/myCustomTabLayout"
            android:background="@color/colorPrimary"
            app:tabSelectedTextColor="@android:color/white"
            app:tabTextColor="@android:color/black">
        </android.support.design.widget.TabLayout>

        <android.support.v4.view.ViewPager
            android:id="@+id/viewPager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>

    <android.support.design.widget.NavigationView
        android:id="@+id/nvView"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:background="@android:color/white"
        app:headerLayout="@layout/nav_header"
        app:menu="@menu/drawer_view" />
</android.support.v4.widget.DrawerLayout>

我的item_row.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:cardBackgroundColor="#fff"
    app:cardCornerRadius="3dp"
    app:cardElevation="3dp"
    app:cardUseCompatPadding="true"
    app:contentPadding="5dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <TextView
            android:id="@+id/rvTitleTv"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="Title"
            android:textColor="#000"
            android:textSize="22sp"
            android:textStyle="bold" />

        <ImageView
            android:id="@+id/rImageView"
            android:layout_width="match_parent"
            android:layout_height="200dp"
            android:adjustViewBounds="true"
            android:background="@drawable/loading"
            android:scaleType="center" />

        <TextView
            android:id="@+id/rPrice"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="150 gdes"
            android:textSize="20dp"
            android:textStyle="bold" />

        <!--<TextView-->
            <!--android:id="@+id/rDescriptionTv"-->
            <!--android:layout_width="match_parent"-->
            <!--android:layout_height="wrap_content"-->
            <!--android:text="This is the post description that"-->
            <!--android:textSize="20sp" />-->
    </LinearLayout>

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

Answer 1

欢迎使用StackOverflow。 def a = A.findOrSaveByField(field) List<B> bList = getBsFromSomeOtherMethod() bList.each { a.addToBs(it) } a.save(failOnError: true) 的设置非常具体。因此，在设置布局管理器和fixedSize属性之前，需要确保已设置适配器。

尝试将您的RecyclerView方法更改为此：

onCreateView