如何从Android中的Firebase获取数据作为模型？

Question

如何从Firebase Cloud Firestore获取数据作为模型？ 您能告诉我完整的代码吗？ 非常感谢。

型号：

public class Vehicle implements Serializable {
    private String Title;
    private int Year;
    private int Price;
    private String City;

    public Vehicle(String title, String city, int price, int year) {
        Title = title;
        City = city;
        Price = price;
        Year = year;
    }

    public String getTitle() {
        return Title;
    }

    public void setTitle(String title) {
        Title = title;
    }

    public int getYear() {
        return Year;
    }

    public void setYear(int year) {
        Year = year;
    }

    public int getPrice() {
        return Price;
    }

    public void setPrice(int price) {
        Price = price;
    }

    public String getCity() {
        return City;
    }

    public void setCity(String city) {
        City = city;
    }
}

MainActivity：

从文档中获取代码，但无法获得车辆标题

DocumentReference docRef = db.collection("cities").document("SF");
docRef.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DocumentSnapshot> task) {
        if (task.isSuccessful()) {
            DocumentSnapshot document = task.getResult();
            if (document.exists()) {
                Log.d(TAG, "DocumentSnapshot data: " + document.getData());
            } else {
                Log.d(TAG, "No such document");
            }
        } else {
            Log.d(TAG, "get failed with ", task.getException());
        }
    }
});

能否请您向我展示代码，例如如何以字符串形式获取标题等等，我必须在回收站视图中显示它，因此我必须从firebase中设置setTitle，从模型中获取getTitle