RecyclerView未显示

Question

我使用了其他答案中给出的技术，例如将依赖关系的版本降级到24 ...和25.0.1。不工作。我将RecyclerView的宽度和高度设置为match_parent。 以下是code.I我在博客应用程序中使用RecyclerView的文章标题和职位说明：

package com.awani.pocketblog; 

import android.content.ClipData; 
import android.content.Intent; 
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.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.TextView; 
import android.widget.Toast; 

import com.firebase.ui.database.FirebaseRecyclerAdapter; 
import com.google.firebase.database.DatabaseReference; 
import com.google.firebase.database.FirebaseDatabase; 

import org.w3c.dom.Text; 

public class MainActivity extends AppCompatActivity { 

private RecyclerView mBlogList; 
private DatabaseReference mDatabase; 

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

    mBlogList = (RecyclerView) findViewById(R.id.blog_list); 
    mBlogList.setHasFixedSize(true); 
    mBlogList.setLayoutManager(new LinearLayoutManager(this)); 
    mDatabase = FirebaseDatabase.getInstance().getReference().child("Blog"); 
} 

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

    FirebaseRecyclerAdapter<Blog,BlogViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Blog, BlogViewHolder>(Blog.class, 
      R.layout.blog_row, 
      BlogViewHolder.class, 
      mDatabase 

    ) { 
     @Override 
     protected void populateViewHolder(BlogViewHolder viewHolder, Blog model, int position) { 
      viewHolder.setTitle(model.getTitle());//model means Blog class over here 
      viewHolder.setDesc(model.getDesc()); 

     } 
    }; 

    mBlogList.setAdapter(firebaseRecyclerAdapter); 
} 

//holder for the recyclerView 
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_description = (TextView) mView.findViewById(R.id.post_description); 
     post_description.setText(desc); 
    } 
} 

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

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    if(item.getItemId()==R.id.action_add){ 
     startActivity(new Intent(MainActivity.this,PostActivity.class)); 
    } 

    return super.onOptionsItemSelected(item); 
} 
} 

日志猫声明，可能会引起这个..

07-08 17:22:10.761 23308-23308/com.awani.pocketblog W/art: Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView 

这是activity_main.xml中代码：

<?xml version="1.0" encoding="utf-8"?> 
<android.widget.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="com.awani.pocketblog.MainActivity"> 

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

</android.widget.RelativeLayout> 

我的Android Studio版本2.3.2是他依赖是25.3.1 和火力依赖是10.0.1 firebase用户界面依赖1.1.1

Answer 1

检查了这一点。我正在使用此代码打印已保存的消息 您可以查看此文档以供参考 尽管我使用了片段，但您可以相应地更改您的代码以进行活动。

import android.app.ProgressDialog; 
import android.content.DialogInterface; 
import android.os.Bundle; 
import android.support.annotation.Nullable; 
import android.support.v7.app.AlertDialog; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.LinearLayoutManager; 
import android.support.v7.widget.RecyclerView; 
import android.support.v7.widget.Toolbar; 
import android.view.View; 
import android.widget.ImageView; 
import android.widget.TextView; 

import com.bumptech.glide.Glide; 
import com.bumptech.glide.load.engine.DiskCacheStrategy; 
import com.example.student.newsapp.R; 
import com.firebase.client.Firebase; 
import com.firebase.ui.database.FirebaseRecyclerAdapter; 
import com.google.firebase.auth.FirebaseAuth; 
import com.google.firebase.database.DatabaseReference; 
import com.google.firebase.database.FirebaseDatabase; 

public class show extends AppCompatActivity { 

RecyclerView recyclerView; 
FirebaseDatabase firebaseDatabase; 
DatabaseReference myRef; 
FirebaseAuth firebaseauth; 
private FirebaseRecyclerAdapter<show_items, ShowDataViewHolder> mFirebaseAdapter; 
private ProgressDialog progressDialog; 

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

@Override 
public void onCreate(@Nullable Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.rvforbookmarks); 
    Firebase.setAndroidContext(this); 
    progressDialog = new ProgressDialog(this); 
    progressDialog.setMessage("Please wait.."); 
    progressDialog.show(); 



    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
    toolbar.setTitle("Bookmarks"); 

    firebaseDatabase = FirebaseDatabase.getInstance(); 

    firebaseauth = FirebaseAuth.getInstance(); 
    final String userid =firebaseauth.getCurrentUser().getUid(); 

    // myRef = firebaseDatabase.getReference("User_Details"); 
    myRef = FirebaseDatabase.getInstance().getReference("User_Details").child(userid); 


    recyclerView = (RecyclerView)findViewById(R.id.rv); 
    recyclerView.setLayoutManager(new LinearLayoutManager(show.this)); 

} 


//View Holder For Recycler View 
public static class ShowDataViewHolder extends RecyclerView.ViewHolder { 
    private final TextView image_title ; 
    private final ImageView image_url; 
    private TextView imge_des; 
    private ImageView btn_delete; 
    private TextView nobookmark; 




    public ShowDataViewHolder(final View itemView) 
    { 
     super(itemView); 
     image_url = (ImageView) itemView.findViewById(R.id.fetch_image); 
     image_title = (TextView) itemView.findViewById(R.id.fetch_image_title); 
     imge_des = (TextView) itemView.findViewById(R.id.fetch_description); 
     btn_delete = (ImageView) itemView.findViewById(R.id.btn_delete); 
     nobookmark = (TextView) itemView.findViewById(R.id.nobookmark); 

    } 

    private void Image_Title(String title) 
    { 
     image_title.setText(title); 
    } 



    private void Image_URL(String title) 
    { 
     // image_url.setImageResource(R.drawable.loading); 
     Glide.with(itemView.getContext()) 
       .load(title) 
       .crossFade() 
       .placeholder(R.drawable.loading) 
       .thumbnail(0.1f) 
       .diskCacheStrategy(DiskCacheStrategy.ALL) 
       .into(image_url); 
    } 


    public void Image_Des(String title) { 
     imge_des.setText(title); 

    } 
} 


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




    mFirebaseAdapter = new FirebaseRecyclerAdapter<show_items, ShowDataViewHolder>(show_items.class, R.layout.showbookamrks, ShowDataViewHolder.class, myRef) { 
     public void populateViewHolder(final ShowDataViewHolder viewHolder, show_items model, final int position) { 
      viewHolder.Image_URL(model.getImage_URL()); 
      viewHolder.Image_Title(model.getImage_Title()); 
      viewHolder.Image_Des(model.getImage_des()); 



      //OnClick Item 
      viewHolder.btn_delete.setOnClickListener(new View.OnClickListener() { 

       @Override 
       public void onClick(final View v) { 
        AlertDialog.Builder builder = new AlertDialog.Builder(show.this); 
        builder.setMessage("Do you want to Delete this data ?").setCancelable(false) 
          .setPositiveButton("Yes", new DialogInterface.OnClickListener() { 
           @Override 
           public void onClick(DialogInterface dialog, int which) { 
            int selectedItems = position; 
            mFirebaseAdapter.getRef(selectedItems).removeValue(); 
            mFirebaseAdapter.notifyItemRemoved(selectedItems); 
            recyclerView.invalidate(); 
            onStart(); 
           } 
          }) 
          .setNegativeButton("No", new DialogInterface.OnClickListener() { 
           @Override 
           public void onClick(DialogInterface dialog, int which) { 
            dialog.cancel(); 
           } 
          }); 
        AlertDialog dialog = builder.create(); 
        dialog.setTitle("Confirm"); 
        dialog.show(); 
       } 
      }); 

       progressDialog.dismiss(); 
     } 

    }; 


    recyclerView.setAdapter(mFirebaseAdapter); 

} 



} 

希望它可以帮助 三江源

Answer 2

Follow This Example Step by Step 

public class MainActivity extends AppCompatActivity implements RecyclerViewClickListener { 

    RecyclerView recyclerView; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_area_list); 
     recyclerView=(RecyclerView)findViewById(R.id.recycler_view1); 

        populateRecyclerView(); 
        recyclerView.setHasFixedSize(true); 
        GridLayoutManager layoutManager = new GridLayoutManager(AreaListActivity.this,3); 
        DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(AreaListActivity.this, layoutManager.getOrientation()); 
        recyclerView.addItemDecoration(dividerItemDecoration); 
        recyclerView.setLayoutManager(layoutManager); 


     //recyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false)); 
    // recyclerView.setLayoutManager(new GridLayoutManager(this,3)); 
    // recyclerView.getLayoutManager().scrollToPosition(5); 




    } 

    public void populateRecyclerView(){ 
     //pass the allAreaList to it 
     RecyclerViewAdapter adapter=new RecyclerViewAdapter(AreaListActivity.this,ArrayList,this); 
     recyclerView.setAdapter(adapter); 
     adapter.notifyDataSetChanged(); 
     //recyclerView.setAdapter(new RecyclerViewAdapter(MainActivity.this,this)); 
    } 


    @Override 
    public void recyclerViewListClicked(View v, int position) { 
     Intent myIntent=new Intent(MainActivity.this,SecondActivity.class); 

     myIntent.putExtra("position",position); 
     startActivity(myIntent); 
     finish(); 
    } 


@Override 
public void onBackPressed() { 
    Intent myIntent=new Intent(MainActivity.this,HomeActivity.class); 
    startActivity(myIntent); 
    finish(); 
} 
} 

RecyclerViewHolder类

公共类RecyclerViewHolder扩展RecyclerView.ViewHolder {

//view holder is for girdview as we used in the listView 
public ImageView imageView,imageView2; 
public RecyclerViewHolder(View itemView) { 
    super(itemView); 
    this.imageView=(ImageView)itemView.findViewById(R.id.image); 
} 

}

适配器类别 公共类RecyclerView_Adapter延伸RecyclerView.Adapter {

//RecyclerView will extend to recayclerview Adapter 
private ArrayList<ModelClass> arrayList; 
private Context context; 
private static RecyclerViewClickListener itemListener; 
//constructor of the RecyclerView Adapter 
RecyclerView_Adapter(Context context,ArrayList<ModelClass> arrayList,RecyclerViewClickListener itemListener){ 
    this.context=context; 
    this.arrayList=arrayList; 
    this.itemListener=itemListener; 
} 

@Override 
public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    //this method will inflate the custom layout and return as viewHolder 
    LayoutInflater layoutInflater=LayoutInflater.from(parent.getContext()); 
    ViewGroup mainGroup=(ViewGroup) layoutInflater.inflate(R.layout.single_item,parent,false); 
    RecyclerViewHolder listHolder=new RecyclerViewHolder(mainGroup); 

    return listHolder; 
} 

@Override 
public void onBindViewHolder(RecyclerViewHolder holder, final int position) { 

    final ModelClass modelClass=arrayList.get(position); 
    //holder 
    RecyclerViewHolder mainHolder=(RecyclerViewHolder)holder; 
    //convert the drawable image into bitmap 
    Bitmap image= BitmapFactory.decodeResource(context.getResources(),modelClass.getImage()); 
    //set the image into imageView 
    mainHolder.imageView.setImageBitmap(image); 
    //to handle on click event when clicked on the recyclerview item and 
    // get it through the RecyclerViewHolder class we have defined the views there 
    mainHolder.itemView.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      //get the position of the image which is clicked 
     itemListener.recyclerViewListClicked(v,position); 
     } 
    }); 

} 

@Override 
public int getItemCount() { 
    return (null!=arrayList?arrayList.size():0); 
} 

}

接口

公共接口RecyclerViewClickListener {

//this is method to handle the event when clicked on the image in Recyclerview 
public void recyclerViewListClicked(View v,int position); 

}

//并在活动中调用此方法 RecyclerView_Adapter adapter = new RecyclerView_Adapter（Wallpaper.this，arrayList，this）; recyclerView.setAdapter（adapter）; adapter.notifyDataSetChanged（）;

@Override 
public void recyclerViewListClicked(View v,int position){ 

    imageView.setImageResource(wallpaperImages[position]); 

}