我对android开发还很陌生，正在尝试用firebase开发应用程序。我用个人资料照片注册，并将照片名称输入数据库。归档到firestore。在底部代码 mImageUrls.add(uri.toString()); 线路不通。但在onsuccess（）中会产生toast，只是我不能将数据添加到数组中。我在oncreateview中初始化了数组( final ArrayList<String> mImageUrls = new ArrayList<>(); )和其他数组一样。我需要你的帮助。

lv = (ListView) rootview.findViewById(R.id.lv_main);

        final ArrayAdapter adapter = new MyAdapter(getActivity(), name_list,date,imgs);

        myref = FirebaseDatabase.getInstance().getReference().child("MusiciansNonSensitive");
        final ArrayList<String> mImageUrls = new ArrayList<>();
        final StorageReference storageReference = FirebaseStorage.getInstance().getReference();
        myref.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
                for (DataSnapshot postSnapshot: snapshot.getChildren()) {
                    String name_value = postSnapshot.child("name").getValue().toString();
                    String province_value = postSnapshot.child("province").getValue().toString();

                    final String url_path = postSnapshot.child("photourl").getValue().toString();
                    StorageReference photo_url = storageReference.child("uploads/"+url_path);
                    photo_url.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                        @Override
                        public void onSuccess(Uri uri) {
                            mImageUrls.add(uri.toString()); // I tried to add Log.d and it adds value every for loop, but after loop it being empty array again.
                        }
                    });

                    //mImageUrls.add("A");
                    name_list.add(name_value);
                    date.add(province_value);

                }
                Log.d("LOGGOGOGOOG",mImageUrls.toString()); // Here being empty 

                //Toast.makeText(getContext(),list.toString(),Toast.LENGTH_LONG).show();
                lv.setAdapter(adapter);
                adapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {

            }
        });