读取Firebase数据库并在RecyclerView中显示：Android

这是我的代码：

Liste.java文件：

public class Liste extends AppCompatActivity{

    RecyclerView myRecyclerview;
    MyAdapter adapter;
    List<Dentist> listDentist;
    FirebaseDatabase FDB;
    DatabaseReference DBR;

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

        myRecyclerview = (RecyclerView) findViewById ( R.id.myRecycler );
        RecyclerView.LayoutManager LM = new LinearLayoutManager ( getApplicationContext ());
        myRecyclerview.setLayoutManager ( LM );
        myRecyclerview.setItemAnimator ( new DefaultItemAnimator () );
        myRecyclerview.addItemDecoration ( new DividerItemDecoration ( getApplicationContext (),LinearLayoutManager.VERTICAL ) );

        listDentist = new ArrayList<> (  );

        adapter = new MyAdapter (listDentist);

        FDB= FirebaseDatabase.getInstance ();
        GetDataFirebase();

 void GetDataFirebase(){
        DBR = FDB.getReference ("dentistes");

        DBR.addChildEventListener ( new ChildEventListener ( ) {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {

                Dentist data = dataSnapshot.getValue (Dentist.class);
                //Add to Arraylist
                listDentist.add ( data );
                //Add list into adapter
                myRecyclerview.setAdapter ( adapter );


            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        } );
    }


public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder>{

        List<Dentist> listArray;

        public MyAdapter (List<Dentist> List){
            this.listArray = List;
        }

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

        @Override
        public void onBindViewHolder(MyViewHolder holder, int position) {
            Dentist data = listArray.get ( position );
            holder.MyText.setText ( data.getName () );
        }
        public class MyViewHolder extends RecyclerView.ViewHolder{
            TextView MyText;

            public MyViewHolder(View itemView) {
                super ( itemView );
                MyText = (TextView)itemView.findViewById ( R.id.textview_dentist );
            }
        }

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

public class Dentist {
    private String Name;

    public String getName() {
        return Name;
    }

    public void setName(String name) {
        Name = name;
    }
}

我有两个问题：

---

• 牙医列表正确显示在my Recyclerview中，但logcat显示“E/Recyclerview:未连接适配器；跳过布局”：我如何更正此问题

• 如果我更改了类模型的结构：例如，我添加了地址和电话号码：我应该如何更改代码，以便在我的Recyclerview中显示每个牙医的姓名、地址和号码

---

要解决这个问题，请参阅下面我的答案：

移动这行代码

adapter = new MyAdapter(listDentist);

内部

onchildaded（）

方法。必须在此方法中声明并使用适配器

您需要通过添加那些私有字段和相应的公共setter和getter来更改

Dentist

类

---

要消除logcat中的警告，请在onCreate方法中设置适配器，并在onChildaded方法中调用adapter.notifyDataSetChanged（）以更新值

    public class Liste extends AppCompatActivity{

    RecyclerView myRecyclerview;
    MyAdapter adapter;
    List<Dentist> listDentist;
    FirebaseDatabase FDB;
    DatabaseReference DBR;

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

        myRecyclerview = (RecyclerView) findViewById ( R.id.myRecycler );
        RecyclerView.LayoutManager LM = new LinearLayoutManager ( getApplicationContext ());
        myRecyclerview.setLayoutManager ( LM );
        myRecyclerview.setItemAnimator ( new DefaultItemAnimator () );
        myRecyclerview.addItemDecoration ( new DividerItemDecoration ( getApplicationContext (),LinearLayoutManager.VERTICAL ) );

        listDentist = new ArrayList<> (  );

        adapter = new MyAdapter (listDentist);

       //Set empty adapter here
        myRecyclerView.setAdapter(adapter);

        FDB= FirebaseDatabase.getInstance ();
        GetDataFirebase();

 void GetDataFirebase(){
        DBR = FDB.getReference ("dentistes");

        DBR.addChildEventListener ( new ChildEventListener ( ) {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {

                Dentist data = dataSnapshot.getValue (Dentist.class);
                //Add to Arraylist
                listDentist.add ( data );
                //Add list into adapter


               adapter.notifyDataSetChanged();

            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        } );
    }


public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder>{

        List<Dentist> listArray;

        public MyAdapter (List<Dentist> List){
            this.listArray = List;
        }

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

        @Override
        public void onBindViewHolder(MyViewHolder holder, int position) {
            Dentist data = listArray.get ( position );
            holder.MyText.setText ( data.getName () );
        }
        public class MyViewHolder extends RecyclerView.ViewHolder{
            TextView MyText;

            public MyViewHolder(View itemView) {
                super ( itemView );
                MyText = (TextView)itemView.findViewById ( R.id.textview_dentist );
            }
        }

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

公共类列表扩展了AppCompative活动{
回收视图myRecyclerview；
MyAdapter适配器；
名单；
FirebaseDatabaseFDB；
数据库参考数据库；
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_liste）；
myRecyclerview=（RecyclerView）findViewById（R.id.myRecycler）；
RecyclerView.LayoutManager LM=新的LinearLayoutManager（getApplicationContext（））；
myRecyclerview.setLayoutManager（LM）；
myRecyclerview.setItemAnimator（新的DefaultItemAnimator（））；
myRecyclerview.addItemDecoration（新的DividerItemDecoration（getApplicationContext（），LinearLayoutManager.VERTICAL））；
listdister=newarraylist（）；
适配器=新的MyAdapter（列表）；
//在此设置空适配器
myRecyclerView.setAdapter（适配器）；
FDB=FirebaseDatabase.getInstance（）；
GetDataFirebase（）；
void GetDataFirebase（）{
DBR=FDB.getReference（“牙医”）；
DBR.addChildEventListener（新的ChildEventListener（）{
@凌驾
公共void onChildAdded（DataSnapshot DataSnapshot，字符串s）{
牙医数据=dataSnapshot.getValue（牙医类）；
//添加到Arraylist
listdistent.add（数据）；
//将列表添加到适配器中
adapter.notifyDataSetChanged（）；
}
@凌驾
公共void onChildChanged（DataSnapshot DataSnapshot，字符串s）{
}
@凌驾
ChildRemoved上的公共void（DataSnapshot DataSnapshot）{
}
@凌驾
已移动ChildMoved上的公共void（DataSnapshot DataSnapshot，字符串s）{
}
@凌驾
已取消的公共void（DatabaseError DatabaseError）{
}
} );
}
公共类MyAdapter扩展了RecyclerView.Adapter{
列表数组；
公共MyAdapter（列表）{
this.listary=List；
}
@凌驾
公共MyViewHolder onCreateViewHolder（视图组父级，int-viewType）{
View View=LayoutInflater.from（parent.getContext（））.flate（R.layout.itemview，parent，false）；
返回新的MyViewHolder（视图）；
}
@凌驾
公共无效onBindViewHolder（MyViewHolder，int位置）{
数据=listary.get（位置）；
holder.MyText.setText（data.getName（））；
}
公共类MyViewHolder扩展了RecyclerView.ViewHolder{
文本查看我的文本；
公共MyViewHolder（查看项目视图）{
超级（项目视图）；
MyText=（TextView）itemView.findViewById（R.id.TextView\u）；
}
}
@凌驾
public int getItemCount（）{
返回listArray.size（）；
}
}
}

---

对于Alex Mamo提到的第二个问题，您需要在牙医类中添加所需的字段以及相应的getter和setter。

1-消息“E/RecyclerView:未连接适配器；跳过布局”总是显示在日志cat.2中-我知道我应该将这些私有字段添加到Destinter类中，但我在如何更改Liste.java文件中的代码方面遇到了障碍。请确保您是从onchildaded（）中的“main”线程调用该语句方法。这是您唯一要执行此操作的地方。也在该方法中声明

myRecyclerview

。它现在起作用了吗？牙医列表正确显示在我的Recyclerview中，但日志再次显示此错误：但这不是问题。我需要我的问题的答案第二个问题。正如前面回答的，首先你需要更改模型类，然后通过每个牙医的孩子循环获取数据。现在可以了吗？我的答案有什么问题？请给我一个解释。

adapter = new MyAdapter(listDentist);

    public class Liste extends AppCompatActivity{

    RecyclerView myRecyclerview;
    MyAdapter adapter;
    List<Dentist> listDentist;
    FirebaseDatabase FDB;
    DatabaseReference DBR;

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

        myRecyclerview = (RecyclerView) findViewById ( R.id.myRecycler );
        RecyclerView.LayoutManager LM = new LinearLayoutManager ( getApplicationContext ());
        myRecyclerview.setLayoutManager ( LM );
        myRecyclerview.setItemAnimator ( new DefaultItemAnimator () );
        myRecyclerview.addItemDecoration ( new DividerItemDecoration ( getApplicationContext (),LinearLayoutManager.VERTICAL ) );

        listDentist = new ArrayList<> (  );

        adapter = new MyAdapter (listDentist);

       //Set empty adapter here
        myRecyclerView.setAdapter(adapter);

        FDB= FirebaseDatabase.getInstance ();
        GetDataFirebase();

 void GetDataFirebase(){
        DBR = FDB.getReference ("dentistes");

        DBR.addChildEventListener ( new ChildEventListener ( ) {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {

                Dentist data = dataSnapshot.getValue (Dentist.class);
                //Add to Arraylist
                listDentist.add ( data );
                //Add list into adapter


               adapter.notifyDataSetChanged();

            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {

            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String s) {

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        } );
    }


public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder>{

        List<Dentist> listArray;

        public MyAdapter (List<Dentist> List){
            this.listArray = List;
        }

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

        @Override
        public void onBindViewHolder(MyViewHolder holder, int position) {
            Dentist data = listArray.get ( position );
            holder.MyText.setText ( data.getName () );
        }
        public class MyViewHolder extends RecyclerView.ViewHolder{
            TextView MyText;

            public MyViewHolder(View itemView) {
                super ( itemView );
                MyText = (TextView)itemView.findViewById ( R.id.textview_dentist );
            }
        }

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