CODEWITHSUNDEEP
javaandroidfirebasefirebase-realtime-databasejava-threads
ofek gani
ofek gani

Reputation: 33

Wait for all async methods finish

I wrote method that contains two async methods that create connection with firebase. I want to finish the method after all the async methods finish. How can i do this? If it was one async method so i was create callBack interface but is not helpful in this situation.

For example:

 public void method(String teamID1,String teamID2)
{
    final ArrayList<String> usersID = new ArrayList<>();

    final DatabaseReference mDatabase1 =  getDatabaseReference(ConstantNames.ROLE_PATH).child ( teamID1 );
    mDatabase1.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            usersID.add(snapshot.getValue().toString());
        }

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

        }
    });

    final DatabaseReference mDatabase2 =  getDatabaseReference(ConstantNames.ROLE_PATH).child ( 2 );
    mDatabase2.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            usersID.add(snapshot.getValue().toString());
        }

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

        }
    });
}

(This method is just for illustration)

I want finish this method when listener of mDatabase1 and listener of mDatabase2 called. How can i do it?

Upvotes: 1

Views: 553

Answers (1)

Frank van Puffelen
Frank van Puffelen

Reputation: 598728

I recommend using the brand new get() method for this. This method does almost the same as addListenerForSingleValueEvent, but:

  • It fixes a race condition that may return stale data from the disk cache.
  • It returns a Task<DataSnapshot>.

That last bit is relevant for you, as it allows you to then use Tasks.whenAll() on the tasks for your two database calls here.

Also see:

Upvotes: 1

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