Anzeigen von Daten in einem RecyclerView

Question

Ich habe dies perfekt mit einem ListView funktioniert, aber beschlossen, meinen Code für die Verwendung von RecyclerView zu aktualisieren.

Ich sehe, es gibt keine Standard-Implementierung, und die Antworten auf ähnliche Fragen sind ziemlich alt.

Verwenden Sie eine Art von Cursor den besten Weg, oder gibt es eine bessere Option?

Dies sind meine Code-Schnipsel für ein Arbeits RecyclerView mit hartcodierte Werte:

MainActivity

recyclerView = (RecyclerView)findViewById(R.id.recycler_view); 
    mLayoutmanager = new LinearLayoutManager(this); 
    recyclerView.setLayoutManager(mLayoutmanager); 

    mAdapter = new recyclerViewDataAdapter(); 
    recyclerView.setAdapter(mAdapter); 

recyclerViewDataAdapter

public class recyclerViewDataAdapter extends RecyclerView.Adapter { 

    @Override 
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 

     //lets populate our recyler view with the item created; 
     //get the view from the layout inflator 
     // third parameter is set to false to prevent viewgroup to attach to root 
     View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.recycler_item,parent,false); 

     // as this method need to return the viewHolder type 
     // need to convert our view to the view holder 
     RecyclerView.ViewHolder viewHolder = new RecyclerView.ViewHolder(view) { 
      @Override 
      public String toString() { 
       return super.toString(); 
      } 
     }; 
     return viewHolder; 
    } 

    @Override 
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) { 

    } 

    @Override 
    public int getItemCount() { 
     return 3000; 
    } 
} 

activity_main

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

recycler_item

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:layout_marginTop="10dp" 
    android:orientation="vertical"> 

    <TextView 
     android:id="@+id/textView" 
     android:layout_width="match_parent" 
     android:layout_height="wrap_content" 
     android:text="Hii " 
     android:textSize="30sp" /> 
</LinearLayout> 

Hier ist meine DatabaseAdapter, die perfekt mit einem Listview gearbeitet:

public class DatabaseHelper extends SQLiteAssetHelper { 

    private static final int DATABASE_VERSION = 1; 

    private static final String DATABASE_NAME = "database9.db"; 
    private static final String BOOKS = "books"; 
    private static final String AUTHORS = "authors"; 

    public DatabaseHelper (Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
     // setForcedUpgrade(); 
    } 

    // Getting all books 
    public ArrayList<Author> getAllAuthors() { 

     ArrayList<Author> authorList = new ArrayList<>(); 

     // Select all query 
     String selectQuery = "SELECT id, name FROM " + AUTHORS + " ORDER BY name_alphabetic"; 

     SQLiteDatabase db = this.getWritableDatabase(); 
     Cursor cursor = db.rawQuery(selectQuery, null); 

     // looping through all rows and adding to list 
     if (cursor.moveToFirst()) { 
      do { 
       // create new author object 
       Author author = new Author(); 
       // set ID and name of author object 
       author.setID(Integer.parseInt(cursor.getString(0))); 
       author.setName(cursor.getString(1)); 
       // pass author object to authorList array 
       authorList.add(author); 
      } while (cursor.moveToNext()); 
     } 

     // return author list 
     return authorList; 
    } 
} 

Answer 1

Ihr versuchen

1. In Ihrem

   Aktivität

   ArrayList<Author> authors = dbHandler. getAllAuthors(); 
   recyclerView.setHasFixedSize(true); 
   
   // ListView 
   recyclerView.setLayoutManager(new LinearLayoutManager(youractivity.this)); 
   
   
   // create an Object for Adapter 
   CardViewDataAdapter1 mAdapter = new CardViewDataAdapter1(authors); 
   
   // set the adapter object to the Recyclerview 
   recyclerView.setAdapter(mAdapter); 
   

2. Ihr Adapter aussehen

   class CardViewDataAdapter1 extends RecyclerView.Adapter<CardViewDataAdapter1.ViewHolder> { 
       private ArrayList<Author> dataSet; 
   
   
   public CardViewDataAdapter1(ArrayList<Author> os_versions) { 
   
       dataSet = os_versions; 
   } 
   
   
   @Override 
   public CardViewDataAdapter1.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) { 
       // create a new view 
       View itemLayoutView = LayoutInflater.from(viewGroup.getContext()).inflate(
         R.layout.recycler_item, null); 
   
       itemLayoutView.setLayoutParams(new RecyclerView.LayoutParams(RecyclerView.LayoutParams.MATCH_PARENT, RecyclerView.LayoutParams.WRAP_CONTENT)); 
   
       // create ViewHolder 
   
       CardViewDataAdapter1.ViewHolder viewHolder = new CardViewDataAdapter1.ViewHolder(itemLayoutView); 
   
       return viewHolder; 
   } 
   
   @Override 
   public void onBindViewHolder(CardViewDataAdapter1.ViewHolder viewHolder, int i) { 
   
       Author fp = dataSet.get(i); 
   
       viewHolder.tv_name.setText(fp.getName()); 
   
   
   
   
       viewHolder.menu = fp; 
   } 
   
   @Override 
   public int getItemCount() { 
   
       return dataSet.size(); 
   } 
   
   public void updateList(List<Author> temp) { 
       dataSet = (ArrayList<Author>) temp; 
       notifyDataSetChanged(); 
   } 
   
   // inner class to hold a reference to each item of RecyclerView 
   public class ViewHolder extends RecyclerView.ViewHolder { 
   
       public TextView tv_name; 
   
   
       public Author menu; 
       public ViewHolder(View itemLayoutView) { 
        super(itemLayoutView); 
   
        tv_name = (TextView) itemLayoutView .findViewById(R.id.tv_name); 
   
   
        } 
   
       } 
   } 
   

3. Ihre recycler_item.xml

   <?xml version="1.0" encoding="utf-8"?> 
       <android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android" 
       xmlns:card_view="http://schemas.android.com/apk/res-auto" 
       android:layout_width="match_parent" 
       android:layout_height="match_parent" 
       card_view:cardCornerRadius="5dp" 
   card_view:cardBackgroundColor="#FFFFFF" 
       card_view:cardUseCompatPadding="true" 
       > 
   <LinearLayout 
       android:layout_width="match_parent" 
       android:layout_height="wrap_content" 
       android:orientation="vertical"> 
       <TextView 
        android:id="@+id/tv_name" 
        android:layout_width="match_parent" 
        android:layout_height="wrap_content" 
        android:text="Enamul"/> 
   
   </LinearLayout> 
   
   </android.support.v7.widget.CardView>