com.google.firebase.database.DatabaseException：无法将 java.lang.String 类型的值转换为 long

Question

按照 firebase 数据库的文档尝试将数据检索到对象以供使用时，我遇到了错误。

这是我的对象模型

public class Cart {

    private String pid, pname, price, discount, quantity;

    public Cart() {
    }

    public Cart(String pid, String pname, String price, String discount, String quantity) {
        this.pid = pid;
        this.pname = pname;
        this.price = price;
        this.discount = discount;
        this.quantity = quantity;
    }

    public String getPid() {
        return pid;
    }

    public void setPid(String pid) {
        this.pid = pid;
    }

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    public String getDiscount() {
        return discount;
    }

    public void setDiscount(String discount) {
        this.discount = discount;
    }

    public String getQuantity() {
        return quantity;
    }

    public void setQuantity(String quantity) {
        this.quantity = quantity;
    }
}

最后，我得到错误的代码和行被注释掉了。

FirebaseRecyclerOptions<Cart> options =
    new FirebaseRecyclerOptions.Builder<Cart>()
    .setQuery(cartListRef.child("User View")
    .child(Prevalent.currentOnlineUser.getPhn_num())
    .child("Products"), Cart.class)
    .build();

FirebaseRecyclerAdapter<Cart, CartViewHolder> adapter =
    new FirebaseRecyclerAdapter<Cart, CartViewHolder>(options) {
        @Override
        protected void onBindViewHolder(@NonNull CartViewHolder holder, int position, @NonNull Cart model)
        {
            holder.jProductName.setText(model.getPname());
            holder.jProductPrice.setText("Price = Rs. " +model.getPrice());
            holder.jProductQuantity.setText("Quantity = " +model.getQuantity());

        }

        @NonNull
        @Override
        public CartViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int i)
        {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.cart_items_layout, parent,false);
            CartViewHolder holder = new CartViewHolder(view);
            return holder;
        }
    };

recyclerView.setAdapter(adapter);
adapter.startListening();

这是我在 Firebase 中的数据库结构。

来自 logcat 的完整 Stacktrace 在这里。

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.dueaoinfo.shoppingapp, PID: 10511
com.google.firebase.database.DatabaseException: Failed to convert a value of type java.lang.String to long
    at com.google.android.gms.internal.firebase_database.zzkt.zzb(Unknown Source:616)
    at com.google.android.gms.internal.firebase_database.zzkt.zza(Unknown Source:301)
    at com.google.android.gms.internal.firebase_database.zzkt.zzb(Unknown Source:0)
    at com.google.android.gms.internal.firebase_database.zzku.zza(Unknown Source:71)
    at com.google.android.gms.internal.firebase_database.zzkt.zzb(Unknown Source:146)
    at com.google.android.gms.internal.firebase_database.zzkt.zza(Unknown Source:0)
    at com.google.firebase.database.DataSnapshot.getValue(Unknown Source:10)
    at com.firebase.ui.database.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:29)
    at com.firebase.ui.database.ClassSnapshotParser.parseSnapshot(ClassSnapshotParser.java:15)
    at com.firebase.ui.common.BaseCachingSnapshotParser.parseSnapshot(BaseCachingSnapshotParser.java:35)
    at com.firebase.ui.common.BaseObservableSnapshotArray.get(BaseObservableSnapshotArray.java:52)
    at com.firebase.ui.database.FirebaseRecyclerAdapter.getItem(FirebaseRecyclerAdapter.java:106)
    at com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:122)
    at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6781)
    at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6823)
    at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5752)
    at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6019)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
    at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
    at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
    at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
    at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3924)
    at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3641)
    at android.support.v7.widget.RecyclerView.consumePendingUpdateOperations(RecyclerView.java:1888)
    at android.support.v7.widget.RecyclerView$1.run(RecyclerView.java:407)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1092)
    at android.view.Choreographer.doCallbacks(Choreographer.java:888)
    at android.view.Choreographer.doFrame(Choreographer.java:816)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:1078)
    at android.os.Handler.handleCallback(Handler.java:873)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:201)
    at android.app.ActivityThread.main(ActivityThread.java:6823)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)

Answer 1

quantity 和 discount 是 Firebase 数据库中的 Long 值，在 Cart 类中它被声明为 String。这是抛出错误。像下面这样声明Cart 类。

public class Cart {

    private String pid, pname, price;
    private Long discount, quantity;

    public Cart() {
    }

    public Cart(String pid, String pname, String price, Long discount, Long quantity) {
        this.pid = pid;
        this.pname = pname;
        this.price = price;
        this.discount = discount;
        this.quantity = quantity;
    }

    public String getPid() {
        return pid;
    }

    public void setPid(String pid) {
        this.pid = pid;
    }

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    public Long getDiscount() {
        return discount;
    }

    public void setDiscount(Long discount) {
        this.discount = discount;
    }

    public Long getQuantity() {
        return quantity;
    }

    public void setQuantity(Long quantity) {
        this.quantity = quantity;
    }
}

希望能解决您的问题。