当数据实时更改时，数据库（firebase）应用程序崩溃

Question

它不仅仅与这些数据有关，错误与 相同 当我将来自其他设备的数据保存到数据库（firebase）中时，应用程序崩溃，其中数据被检索并设置到其他设备的回收视图中

onDataChange 是实时的，当数据更改时会自动调用它
通知类

public class Notifications {
    private String Name;
    private String Email;
    private String Message;
    private String Time;
    private String Date;

    public Notifications() {

    }

    public Notifications(String Name, String Email, String Message, String Time, String Date) {
        this.Name = Name;
        this.Email = Email;
        this.Message = Message;
        this.Time = Time;
        this.Date = Date;
    }

    public String getName() {
        return Name;
    }

    public String getEmail() {
        return Email;
    }

    public String getMessage() {
        return Message;
    }

    public String getTime() {
        return Time;
    }

    public String getDate() {
        return Date;
    }
}

DatabaseReference userref = FirebaseDatabase.getInstance().getReference().child("Notification");
        userref.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                if (dataSnapshot.exists()) {
                    notificationList.clear();
                    for (DataSnapshot userSnapshot : dataSnapshot.getChildren()) {

                        Notifications notifications = userSnapshot.getValue(Notifications.class);

                        notificationList.add(notifications);

                    }
                    Collections.reverse(notificationList);
                    mAdapter = new Adapter_Notification(notificationList);
                    mRecyclerView.addItemDecoration(new DividerItemDecoration(getContext(), LinearLayoutManager.VERTICAL));

                    mRecyclerView.setAdapter(mAdapter);


                }

            }

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

            }
        });

显示此错误

com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.Boolean to type com.example.simpleapplocker.Notifications

排队

 notificationList.add(notifications);

启动后检索该数据并显示在回收视图中 这意味着数据存在或者可能创建了通知但没有上传其他数据并且可能调用了这个函数？？

Answer 1

试试这个方法，对我有用

FirebaseDatabase database = FirebaseDatabase.getInstance();
                DatabaseReference myRef = database.getReference("Notification");
                myRef.addChildEventListener(new ChildEventListener() {
                    @Override
                    public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
                        if(dataSnapshot.exist()) {
        Notifications notifications = userSnapshot.getValue(Notifications.class);
        
                                notificationList.add(notifications);
        
                            }
                            Collections.reverse(notificationList);
                            mAdapter = new 
      Adapter_Notification(notificationList);
                            mRecyclerView.addItemDecoration(new DividerItemDecoration(getContext(), LinearLayoutManager.VERTICAL));
        
                            mRecyclerView.setAdapter(mAdapter);
     
                    }
        
                    @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) {
        
                    }
                });

Answer 2

Notifications notifications = userSnapshot.getValue(Notifications.class);

在这一行中，您会收到一条错误消息，即布尔对象无法转换为通知。如果您将该子项的值设置为 true 或 false（不带双引号），则可能会出现这种情况。再次查看并尝试在要设置为子值的“true”或“false”周围添加双引号。