Question

我将数据放入Firebase文档中

<ion-back-button class="btnmy11" defaultHref="/" [ngClass]="{'back-hide': menuIsHidden==true}"></ion-back-button>

该帖子属于“关注”类别

try {
                String uid = user.getUid();
                String title  = InputProductTitle.getText().toString();
                Double price = Double.valueOf(InputProductPrice.getText().toString());
                String categories = CategoryDataFromPreviousIntent.split("&&")[0];
                String subCategories = CategoryDataFromPreviousIntent.split("&&")[1];
                String dateAdded = new Date().toString();
                String description = InputProductDescription.getText().toString();
                Post newPost = new Post(uid,title, price, categories, subCategories, dateAdded, false,description);

                mFirebase.collection("NewPost").document().set(newPost).addOnSuccessListener(new OnSuccessListener<Void>() {
                    @Override
                    public void onSuccess(Void aVoid) {
                        Toast.makeText(getApplicationContext(), "Added", Toast.LENGTH_SHORT).show();
                    }

                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        Toast.makeText(getApplicationContext(), "Error" + e.getMessage(), Toast.LENGTH_SHORT).show();
                    }
                });
            } catch (Exception e) {
                Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_LONG).show();
            }

我已宣布出价为TreeMap类型。但是当我试图像这样从我的应用程序中的Firebase取回数据

public class Post {
private String addedBy;
private String title;
private Double price;
private String categories;
private String subCategories;
private TreeMap<String,Double> bids;
private String dateAdded;
private boolean status;
private String imageLink;
private String soldTo;
private String description;
public Post(){}

public Post(String addedBy, String title ,Double price, String categories, String subCategories, String dateAdded, boolean status, String description) {
    this.addedBy = addedBy;
    this.title = title;
    this.price = price;
    this.categories = categories;
    this.subCategories = subCategories;
    this.dateAdded = dateAdded;
    this.status = status;
    this.imageLink = "";
    this.soldTo = "";
    this.description = description;
    this.bids = new TreeMap<String, Double>();
}

我在行中收到以下错误 private FirebaseFirestore db = FirebaseFirestore.getInstance(); private CollectionReference notebookRef = db.collection("NewPost"); public void loadNotes() { notebookRef.get() .addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() { @Override public void onSuccess(QuerySnapshot queryDocumentSnapshots) { for (QueryDocumentSnapshot documentSnapshot : queryDocumentSnapshots) { Map<String, Object> allData = documentSnapshot.getData(); Post obj = documentSnapshot.toObject(Post.class); } }); }

说

Post obj = documentSnapshot.toObject(Post.class);

我现在将Post类的出价设置为HashMap，我一直使用TreeMap，但是现在当Firebase的数据来临时，HashMap来了，为什么会这样。

我尝试将TreeMap转换为HashMap并能正常工作，但随后我想使用TreeMap。

任何人都可以向我解释。谢谢。

Answer 1

将其声明为Map，然后尝试使用树作为构造函数的参数创建树形地图对象

参数1的类型为java.util.TreeMap，得到了java.util.HashMap

1 个答案: