如何获取具有特定值的字段的文档的文档ID？

要解决此问题，请尝试以下代码行：

FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
CollectionReference deliveryRef = rootRef.collection("delivery");
Query nameQuery = deliveryRef.whereEqualTo("itemName", "eggroll");
nameQuery.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
    @Override
    public void onComplete(@NonNull Task<QuerySnapshot> task) {
        if (task.isSuccessful()) {
            for (QueryDocumentSnapshot document : task.getResult()) {
                Log.d(TAG, document.getId());
            }
        }
    }
});

您的logcat中的输出将是以下文档ID：

8jy6 ... fcrm