private void addBillToList(String concept, int amount) {
if (concept == "END") return;
Bill bill = new Bill(concept, amount);
if (firstBill == null) {
firstBill = bill;
return;
}
Bill current = firstBill;
while (current != null) {
if (current.getNextBill() == null) {
current.setNextBill(bill);
return;
}
current = current.getNextBill();
}
return;
}
