Firebase "Failed to convert a value of type java.util.HashMap to int"

Question

At this line of my code in my OnDataChange() method in the ValueEvenListener:

int latest = dataSnapshot.getValue(Integer.class);

I'm getting a DatabaseException with the error Failed to convert a value of type java.util.HashMap to int.

However, in my database, you can take a look at the image below:

It is obviously not a HashMap but an int. Is this a bug or am I doing something wrong? What can I do to fix it? Why is it retrieving a Hashmap when the value is int?

Full dataSnapshot:

final DatabaseReference database = FirebaseDatabase.getInstance().getReference();
        database.child("Campaigns").child(key).child("count");
        database.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                int latest = dataSnapshot.getValue(Integer.class);
                button.setText(latest + "");
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                Toast.makeText(context, context.getString(R.string.error) + ": " + databaseError.getMessage(), Toast.LENGTH_SHORT).show();
            }
        });

Database:

Campaigns:{
  -JDKKDJIIDJFIDJKDK:{
      count:2432
   }
}

share the declaration of dataSnapshot and also what you are adding to it — Viral Patel
– Viral Patel, Commented Aug 9, 2016 at 8:21
if the dataSnapshot has only the value that u want..in our case 2580 try int latest = Integer.parseInt(dataSnapshot); also, maybe you should convert datasnapshot.toString() but i dont remember EDIT: if this doesnt work please Log the dataSnapshot so i can provide you with full answer — Antonios Tsimourtos
– Antonios Tsimourtos, Commented Aug 9, 2016 at 8:54
It didn't work, I get a NumberFormatException. And please explain what do you mean by "Log the dataSnapshot". Thank you for trying to help — Ali Bdeir
– Ali Bdeir, Commented Aug 9, 2016 at 9:07
inside the OnDataChange insert this line - > Log.w("eeee", dataSnapshot.toString()); , then look in the logcat after you run the app, and search for something with the name "eeee" — Antonios Tsimourtos
– Antonios Tsimourtos, Commented Aug 9, 2016 at 9:10

Ali Bdeir · Accepted Answer · 2016-08-09 09:26:41Z

7

It turns out I had to child dataSnapshot to my destination again. E.g:

int latest = dataSnapshot.child("Campaigns").child(key).child("count").getValue(Integer.class);

By default dataSnapshot is actually my whole database.

answered Aug 9, 2016 at 9:26

Ali Bdeir

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Comments

Sam Stern · Accepted Answer · 2016-08-09 15:51:22Z

Your ValueEventListener is attached to the whole database.

// This line gets a reference to the whole database
final DatabaseReference database =  FirebaseDatabase.getInstance().getReference();

// This line creates a child DatabaseReference, but you don't assign
// the child to a variable
database.child("Campaigns").child(key).child("count");

// This line adds a ValueEventListener to the whole database
database.addValueEventListener(new ValueEventListener() {

What you want instead is this:

final DatabaseReference database = FirebaseDatabase.getInstance().getReference()
final DatabaseReference countRef = database.child("Campaigns").child(key).child("count")
countRef.addValueEventListener(new ValueEventListener() {
    // ...
});

You can see that in the latter example the ValueEventListener is attached to the child reference, not to the root.

Antonios Tsimourtos · Accepted Answer · 2016-08-09 09:30:40Z

3

This should work if we assume that the dataSnapshot is right.

final DatabaseReference database = FirebaseDatabase.getInstance().getReference();
database = database.child("Campaigns").child(key).child("count"); // replaced

        database.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                int latest = Integer.valueOf(dataSnapshot.getValue().toString()); // replaced
                button.setText(latest + "");
            }

            @Override
        public void onCancelled(DatabaseError databaseError) {
            Toast.makeText(context, context.getString(R.string.error) + ": " + databaseError.getMessage(), Toast.LENGTH_SHORT).show();
        }
    });

Reminder : addValueEventListener will run everytime there is a change in the dataSnapshot. If you want to run it just once use addListenerForSingleValueEvent instead.

edited Aug 9, 2016 at 9:30

answered Aug 9, 2016 at 9:17

Antonios Tsimourtos

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6 Comments

Ali Bdeir Over a year ago

I'll try it. And addValueEventListener is what I want,, thanks

Antonios Tsimourtos Over a year ago

if this doesn't work that means is something wrong with the dataSnapshot and that you should show it even if its 20 line of codes. Or edit your question and insert an example of how your data structure is.

Ali Bdeir Over a year ago

Now it gives me a NumberFormatException since dataSnapshot.getValue().toString() is returning the same as dataSnapshot.toString() , which is a HUGE string (20+ lines)

Antonios Tsimourtos Over a year ago

edit the line "database.child("Campaigns").child(key).child("count");" to "database = database.child("Campaigns").child(key).child("count");"

Antonios Tsimourtos Over a year ago

okay glad you came up with a solution, you could post it as an aswer for the other users

|

Aaraf Rao · Accepted Answer · 2022-09-10 17:25:41Z

0

HashMap<String, String> hashMap = (HashMap<String, String>) dataSnapshot1.getValue();
                System.out.println("hehe " + hashMap);
                String demo = String.valueOf(hashMap.get("sets"));
                String name = String.valueOf(hashMap.get("name"));

The COde Above ^^^ Worked fine for me.

answered Sep 10, 2022 at 17:25

Aaraf Rao

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