android - 从 Firebase 数据库检索数据并将其设置到 recyclerview 适配器中

Question

我想从 firebasedatabase 读取数据并显示到 recyclerview 中通过 orderbychild 方法从 FirebaseDatabase 检索数据。我想读取那个 child 的数据，该 child 的电子邮件与我当前从 app 登录的 userremail 匹配。

这是我的 Firebase:

我已经成功完成了第一部分，但我在第二部分中遇到了问题，如何将检索到的数据传递给 recyclerview 适配器。

例如，每当用户从 mobeen@gmail.com 登录时我读取了他的位置和 Ticket_no 并将该数据显示到 recyclerview 中。我遇到了这条线的问题

programinglist.setAdapter(new myadapter(this,  modl1));

我应该在哪里将我的 modl1 ( ArrayList<model> modl1 ) 传递给 recyclerview.setadapter

public class recyclierview extends AppCompatActivity {
public  RecyclerView programinglist;
    DatabaseReference b1, b2;
    public ArrayList<model> modl1;
    @Override
    protected void onCreate(Bundle savedInstanceState)
 {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recyclierview);
          programinglist = findViewById(R.id.my_recycler_view);
        programinglist.setLayoutManager(new LinearLayoutManager(this));
        modl1  =new ArrayList<model>();
      readdata(new firebasecallback() {
          @Override
          public void oncallback(ArrayList<model> list) {
              Log.v("aliraza" , "value oncalback" + list.get(0).getTicket_no());
          }
      });
}  

 private  void readdata(final firebasecallback firebasecallback)
    {
        b1= FirebaseDatabase.getInstance().getReference();
        b2=b1.child("tasks");
        b2.orderByChild("email").equalTo(MainActivity.email).addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {


                model m = new model();
                String location = dataSnapshot.child("location").getValue().toString();
                String tickeno = dataSnapshot.child("ticket_no").getValue().toString();
                Log.v("ALI", "family value " +location);
                Log.v("ALI", "family value " + tickeno);
                m.setLocation(location);
                Log.v("ALI", "location " +m.getLocation());
                m.setTicket_no(tickeno);
                modl1.add(m);
                Log.v("ALI", "family value " +modl1.get(0).getTicket_no());
                firebasecallback.oncallback(modl1);
            }

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

            }

            @Override
            public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

            }

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

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });
        programinglist.setAdapter(new myadapter(this,  modl1));// where should i call this setadapter function of recyclierview.enter code here



    }
    private  interface firebasecallback
    {
        void oncallback( ArrayList<model> list);
    }
}

Answer 1

初始化你的数组列表和适配器；

 public ArrayList<model> modl1=new ArrayList();
 private myadapter adapter;

在onCreate()方法中使用空白列表初始化适配器并将适配器设置为recyclerview。

adapter=new myadapter(this,  modl1);
programinglist.setAdapter(adapter);

然后在适配器中创建一个方法addItem()。

public void addItem(model item){
   list.add(item); // add item to your adapter list
   notifyItemInserted(list.size());
 }

onChildAdded() 方法的更改

modl1.add(m); //remove this line 
 firebasecallback.oncallback(m);

 readdata(new firebasecallback() {
          @Override
          public void oncallback(model m) {
          modl1.add(m);
          adapter.add(m);
              Log.v("aliraza" , "value oncalback" + list.get(0).getTicket_no());

          }
      });

您可以删除 firebasecallback 方法，因为不需要它，并直接在 onChildAdded() 方法中将项目添加到适配器。只需从 onCreate()

调用 readdata() 方法即可

private  void readdata()
    {
        b1= FirebaseDatabase.getInstance().getReference();
        b2=b1.child("tasks");
        b2.orderByChild("email").equalTo(MainActivity.email).addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {


                model m = new model();
                String location = dataSnapshot.child("location").getValue().toString();
                String tickeno = dataSnapshot.child("ticket_no").getValue().toString();
                Log.v("ALI", "family value " +location);
                Log.v("ALI", "family value " + tickeno);
                m.setLocation(location);
                Log.v("ALI", "location " +m.getLocation());
                m.setTicket_no(tickeno);
                modl1.add(m);
                Log.v("ALI", "family value " +modl1.get(0).getTicket_no());
                adapter.add(m);
            }

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

            }

            @Override
            public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

            }

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

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {

            }
        });




    }

希望这会有所帮助!