codenull2.java

// Code From Clean Code Book   
public void registerItem(Item item) {
 if (item != null) {
  ItemRegistry registry = peristentStore.getItemRegistry();
  if (registry != null) {
   Item existing = registry.getItem(item.getID());
   if (existing.getBillingPeriod().hasRetailOwner()) {
    existing.register(item);
   }
  }
 }
}