{"id":17554,"date":"2022-10-25T15:15:47","date_gmt":"2022-10-25T09:45:47","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-code-does-not-wait-for-firebasedatabase-to-be-read\/"},"modified":"2022-10-25T15:15:47","modified_gmt":"2022-10-25T09:45:47","slug":"solved-code-does-not-wait-for-firebasedatabase-to-be-read","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-code-does-not-wait-for-firebasedatabase-to-be-read\/","title":{"rendered":"[Solved] Code does not wait for FirebaseDatabase to be read"},"content":{"rendered":"

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As Selvin commented: data is loaded from Firebase asynchronously. You can’t reliably wait for the data to become available. See Setting Singleton property value in Firebase Listener.<\/p>\n

The solution is to move the code that needs the data from Firebase into<\/strong> the onDataChange<\/code> in checkDataNew<\/code>:<\/p>\n

fun checkDataNew() {\n    var rootRef=FirebaseDatabase.getInstance().getReference(\"BG Data\")\n    \/\/ Read from the database\n    rootRef.addValueEventListener(object : ValueEventListener {\n        override fun onDataChange(dataSnapshot: DataSnapshot) {\n            var isKeyFound = false; \/\/ local variables\n            var foundKey;\n            \/\/ This method is called once with the initial value and again\n            \/\/ whenever data at this location is updated.\n            for(data:DataSnapshot in dataSnapshot.children)\n            {\n                var oldEvent=data.child(\"recentEvent\").getValue().toString()\n                var oldDate:String=data.child(\"calendarTime\").getValue().toString()\n                var oldEmailID:String=data.child(\"emailID\").getValue().toString()\n\n                if(oldEvent.equals(recentEvent) && oldDate.equals(calendarTime) && oldEmailID.equals(emailID)) {\n                    foundKey = data.key.toString()\n                    isKeyFound = true\n                }\n            }\n\n            \/\/ TODO: process the result here\n            if (isKeyFound) {\n              ...\n            } else {\n              ...\n            }\n        }\n\n        override fun onCancelled(error: DatabaseError) {\n            \/\/ Failed to read value\n        }\n    })\n}\n<\/code><\/pre>\n
Alternatively you can define your own callback interface, pass that into checkDataNew<\/code> and invoke it from within there. For an example of this, see getContactsFromFirebase() method return an empty list.<\/p>\n
This is a quite common question. So in addition to the links I already provided, I recommend you check out some of these:<\/p>\n