I am using below function having a query to retrieve data from firebase
   DatabaseReference rootRef;
 @Override
protected void onCreateonCreate(){
 rootRef = FirebaseDatabase.getInstance().getReference();
        getDriverStatus();
}
     public void getDriverStatus(){
            query = rootRef.child("Drivers").orderByChild("email");
            ValueEventListener valueEventListener = new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    for(DataSnapshot ds : dataSnapshot.getChildren()) {
                        Log.d("Firebase","Searching driver..."); //works correctly
 String phone = ds.child("mobile").getValue(String.class);
                        Log.d("Firebase",phone); //phone=null
                        if(phone.equalsIgnoreCase("1234")) //Exception + App crash here
{
                            Log.d("Firebase","Driver found");
                            status=ds.child("status").getValue(String.class);
                            break;
                        }
                    }
                }
@Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        Log.d("Firebase", databaseError.getMessage());
    }
};
query.addListenerForSingleValueEvent(valueEventListener);
}
Following is what my test looks like:
Basically i want to get a Driver data with mobile no: say "1234". But my app crashes at the point if(phone.equalsIgnoreCase("1234")) and gives me the following error:
 java.lang.NullPointerException: String.equalsIgnoreCase on a null object reference
Can any body tell me what is wrong with the code. Thanks in advance...!

