问题
I have reviewed other similar posts before posting this, mine is different I am current retrieving a list of download urls from my Firestore data base, then trying to download those images from my firebase storage to display them in a gridview.
This is my code so far:
final Query chatRoomMsgs = db.collection("chatrooms").document(chatRoomID).collection("Messages").whereEqualTo("sentby", firebaseAuth.getUid());
chatRoomMsgs.get()
.addOnSuccessListener(new OnSuccessListener<QuerySnapshot>() {
@Override
public void onSuccess(QuerySnapshot queryDocumentSnapshots) {
ArrayList<String> sentPicsURLS = new ArrayList<String>();
for(QueryDocumentSnapshot documentSnapshot: queryDocumentSnapshots){
for(int i = 0; i < queryDocumentSnapshots.size(); i++) {
sentPicsURLS.add(documentSnapshot.get("image").toString());
if(i == (queryDocumentSnapshots.size()-1)){
//now download the images and place them into the proper view
for(int z = 0; z < sentPicsURLS.size(); z++){
}
}
}
}
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
}
});
This is where the images should be pulled and pushed into a gridview:
for(int z = 0; z < sentPicsURLS.size(); z++){
//right here
}
But I am having trouble creating an adapter that can handle this. I have a valid gridview in the activity and I have a layout file that contains an imageview with a ID.
final ArrayAdapter arrayAdapter = new ArrayAdapter(Chatroom.this, R.layout.chatroom_sent_images,R.id.sent_iv);
sentPics.setAdapter(arrayAdapter);
sentPics.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//empty for now
}
});
The part I am missing (seems to be) where I actually loop through sentPicsURLS and then add them to the adapter... maybe with something like arrayAdapter.addAll(sentPicsURLS); inside the //right here for loop?
Right now the gridview is showing empty without even the default image view included in R.layout.chatroom_sent_images. I feel like I am so close, what am I missing? Thanks!
Edit Here is my chatroom database structure, every chatroom and chatroom message is structured the same way.
回答1:
As I see in your screenshot, your document hols only a single image. So to solve this, there is no need for an extra inner for-loop. To create a list of those images, please use the following lines of code:
Query chatRoomMsgs = db.collection("chatrooms").document(chatRoomID)
.collection("Messages").whereEqualTo("sentby", firebaseAuth.getUid());
chatRoomMsgs.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
ArrayList<String> sentPicsURLS = new ArrayList<>();
for (QueryDocumentSnapshot document : task.getResult()) {
sentPicsURLS.add(document.getString("image"));
}
//Do what you need to do with your list
Log.d(TAG, "List size: " + sentPicsURLS.size());
}
}
});
Be also aware that Firebase APIs are asynchronous and you can use that list only inside the callback. Now, the result in your logcat will be size of your list.
来源：https://stackoverflow.com/questions/60819377/how-to-populate-a-gridview-with-images-retreieved-from-firebase-storage