相关疑难解决方法(0)

我希望将每个特定对象的dataSnapshot和key的引用传递给自定义的"Message"对象.

我已经尝试在Message.class中使用键'String key',但它似乎返回null.

这是我的Message对象当前的方式:

public class Message {

    private String key;
    private String sender_id;
    private String sender_username;
    private String receiver_username;
    private String receiver_id;
    private String chat_id;
    private String message;
    private Firebase ref;
    private double createdAt;
    private boolean read;

    public Message() {
        // empty default constructor, necessary for Firebase to be able to deserialize messages
    }

    public String getKey() { return key; }
    public String getSender_id() { return sender_id; }
    public String getSender_username() { return sender_username; }
    public String getReceiver_username() { …

我想从这个 firebase-database（下图）获取数据到一个 ArrayListOf< Product> 当Productclass 是：

data class Product(
val title:String,
val photoURL:String,
val description:String,
val price:Double
)
//and i want to make an array like this 
val r = arrayListOf<Product>()

所以基本上我想制作 Firebase_Database_products 的数组列表，感谢任何帮助:)