java - 从 FirebaseDatabase 检索所有用户

Question

我正在从 firebase 数据库中检索所有用户并将它们显示在 recyclerView 中。它显示城镇、用户名和图像。我能够检索，但它只显示一个用户而不是所有用户。数据库有很多用户，但只显示一个。任何建议都会有帮助。

这是检索用户的位

    public void showUsersList() {

    mdatabaseRef = FirebaseDatabase.getInstance ().getReference ( "Users" );

        mdatabaseRef.addValueEventListener ( new ValueEventListener () {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                mcontacts.clear ();

                for (DataSnapshot postSnapshot : dataSnapshot.getChildren ()) {

                   Contacts contactsz = dataSnapshot1.getValue (Contacts.class);
                    mcontacts.add ( contactsz );

                }

                mAdapter = new UsersAdapter ( getApplicationContext () , mcontacts );
                recyclerView.setAdapter ( mAdapter );

            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

                Toast.makeText ( FindFriendsActivity.this , " " , Toast.LENGTH_SHORT ).show ();

            }
        } 



    }

这是适配器类

     private Context mcontext;
    private List<Contacts> mcontacts;

    public UsersAdapter(Context context, List<Contacts> contacts){

        mcontext = context;
        mcontacts = contacts;

    }


    @NonNull
    @Override
    public UsersViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup , int i) {

        View v = LayoutInflater.from ( mcontext ).inflate ( R.layout.users_display_layout, viewGroup, false );
        return new UsersViewHolder ( v );

    }

    @Override
    public void onBindViewHolder(@NonNull UsersViewHolder usersViewHolder , int i) {

        Contacts contactsCurrent  = mcontacts.get ( i );
        usersViewHolder.nameOfUser.setText ( contactsCurrent.getName () );
        usersViewHolder.nameOfTown.setText ( contactsCurrent.getTownname () );

        Picasso.get ().load ( contactsCurrent.getImage () ).into ( usersViewHolder.usersImage );

    }

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

    public class UsersViewHolder extends RecyclerView.ViewHolder{

             public TextView nameOfUser;
             public TextView nameOfTown;
             public CircleImageView usersImage;

        public UsersViewHolder(@NonNull View itemView) {
            super ( itemView );

            nameOfUser = itemView.findViewById ( R.id.user_profile_name );
            nameOfTown = itemView.findViewById ( R.id.user_town_name );
            usersImage = itemView.findViewById ( R.id.users_profile_image );


        }
    }

}
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这是联系人类

public class Contacts {

    public String Name,townname,image;


    public Contacts(){

    }


    public Contacts(String name , String townname , String image) {
        Name = name;
        this.townname = townname;
        this.image = image;

    }


    public String getName() {
        return Name;
    }

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

    public String getTownname() {
        return townname;
    }

    public void setTownname(String townname) {
        this.townname = townname;
    }

    public String getImage() {
        return image;
    }

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


  [1]: /image/dFD6z.jpg

Answer 1

我不认为 Firebase 可以让你获取所有用户帐户信息，这是我在一个项目中工作时所做的，当他们以这种格式注册时，我使用 readtime DataBase 来保存用户信息(稍后可以使用 Uid 更新信息) ，然后为 recyclerView 获取此数据库字段。

注意:应该使用用户身份验证 UID 来获取数据。

对于这种情况，也可以为 recyclerView 尝试使用此方法，而不是 onDataChange。

mFirebaseDatabaseRef.child("Users").addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {

                String retrievename = String.valueOf((String) dataSnapshot.child("Name").getValue());
                String retrievecity = String.valueOf((String) dataSnapshot.child("townname").getValue());
                String retrieveProfileImage = String.valueOf((String) dataSnapshot.child("image").getValue());

                if (!retrievename.equals("null")) {

                    usersnames.setText ( retrievename );
                    userstown.setText ( retrievecity );
                   Picasso.get().load ( retrieveProfileImage ).into ( circleImageView );
                }
                mAdapter.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) { }
        });
    }