Firebase Firestore get data from collection

Question

I want to get data from my Firebase Firestore database. I have a collection called user and every user has collection of some objects of the same type (My Java custom object

Answer 1

Here is a simplified example:

Create a collection "DownloadInfo" in Firebase.

And add a few documents with these fields inside it:

file_name (string), id (string), size (number)

Create your class:

public class DownloadInfo {
    public String file_name;
    public String id;
    public Integer size;
}

Code to get list of objects:

FirebaseFirestore db = FirebaseFirestore.getInstance();

db.collection("DownloadInfo")
        .get()
        .addOnCompleteListener(new OnCompleteListener() {
            @Override
            public void onComplete(@NonNull Task task) {
                if (task.isSuccessful()) {
                     if (task.getResult() != null) {
                            List downloadInfoList = task.getResult().toObjects(DownloadInfo.class);
                            for (DownloadInfo downloadInfo : downloadInfoList) {
                                doSomething(downloadInfo.file_name, downloadInfo.id, downloadInfo.size);
                            }
                        }
                    }
                } else {
                    Log.w(TAG, "Error getting documents.", task.getException());
                }
            }
        });