Get last node in Firebase database Android

Question

I want to get item in the last node added in firebase database from my Android. You can see on the image below i\'m not sure how to get the specific node, because unique key

Answer 1

I prefer to write and retrieve data through objects. MyObject is POJO.

@Override
public void onDataChange(DataSnapshot dataSnapshot) {
    for (DataSnapshot data : dataSnapshot.getChildren()) {
        MyObject myObject = data.getValue(MyObject.class);
        Log.i(TAG, data.getKey() + " = " + myObject.toString());
    }
}

Answer 2

This might work:

DatabaseReference db = FirebaseDatabase.getInstance().getReference().child("mp");
Query query = db.orderByKey().limitToLast(1);
query.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot child: dataSnapshot.getChildren()) {
            Log.d("User key", child.getKey());
            Log.d("User val", child.child("message").getValue().toString());
        } 
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        // TODO: Handle errors.
    }
});

Answer 3

Try this:

DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference();
Query lastQuery = databaseReference.child("mp").orderByKey().limitToLast(1);
lastQuery.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        String message = dataSnapshot.child("message").getValue().toString();
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        // Handle possible errors.
    }
});

Hope this helps!

Answer 4

console.log('last messages', messages[messages.length-1]);