43rd: Returns an array or set of 0 lengths, not NULL

Private Final list<cheese> Cheesesinstock = ...;  Public cheese[] Getcheese () {    if(cheesesinstock.size () = =0        )returnnull ;    ...}

If NULL is returned,

Processing the code on the client requires additional code to handle the null return value:

cheese[] cheeses = shop.getcheeses (); if null && arrays.aslist (cheese). Contains (Cheese.stilton))    System.out.println (" Jolly good ");}

Instead of:

cheese[] cheeses = shop.getcheeses (); if (arrays.aslist (cheese). Contains (Cheese.stilton))    System.out.println ("Jolly good");}

It is considered better to have a null return value than a zero-length array, because it is not necessary to avoid the overhead required to allocate the array.

1. Unless the analysis shows that this is a method that does affect performance

2. It is possible to return the same 0-length array for a call that does not return any type

The collections class provides a way to return the same immutable empty collection when an empty collection is required:

 Public List<cheese> getcheeselist () {    if(cheeseinstock.isempty)) {        return  collections.emptylist ();     Else        return New Arraylist<cheese>(Cheesesinstock);}

43rd: Returns an array or set of 0 lengths, not NULL