Android Studio FireStore 合集

Question

java.lang.NullPointerException: Attempt to invoke virtual method 'long java.lang.Long.longValue()' on a null object reference
        at com.vedev.celebr8.activity.DBqueries$3$1.onComplete(DBqueries.java:162)
        at com.google.android.gms.tasks.zzj.run(Unknown Source:4)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:201)
        at android.app.ActivityThread.main(ActivityThread.java:6810)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)

我到处都见过

firebaseFirestore.collection("PRODUCTS").document(String.valueOf(task.getResult().get("product_ID_"+x)))
.get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
    @Override
    public void onComplete(@NonNull Task<DocumentSnapshot> task) {
        if (task.isSuccessful()) {

            wishListModelList.add(new WishListModel(String.valueOf(task.getResult().get("product_image_1"))
                    , String.valueOf(task.getResult().get("product_title"))
                    , (long) task.getResult().get("free_coupons")
                    , String.valueOf(task.getResult().get("average_rating"))
                    , (Long) task.getResult().get("total_ratings")
                    , String.valueOf(task.getResult().get("product_price"))
                    , String.valueOf(task.getResult().get("cutted_price"))
                    , (boolean) task.getResult().get("COD")));

            MyWishListFragment.wishListAdapter.notifyDataSetChanged();
        } else {
            String error = task.getException().getMessage();
            Toast.makeText(context, error, Toast.LENGTH_LONG).show();
        }
    }
});

我预计此代码的输出将帮助我在我的电子商务应用中查看我的愿望清单，但它不起作用。

Answer 1

据我了解，您希望检索您的 Firestore 集合。我在文档中搜索，发现如何使用 java 来connect and retrieve your collections。