When a collection is returned from a method, and if the collection to be returned is null , then it is always better to return an empty collection.
There are methods available in Collections class to return empty collection with respect to Map, List and Set.
public static void main(String input1)
//Write code here
Matrix<String> mt = new Matrix<String>();
Collection<String> lstStr = mt.processColl(null);
public Collection<T> processColl(Collection<T> coll)
if(null == coll)
//return new ArrayList<String>();
In the above code, Collections.emptyList() returns an immutable list. So , the developer needs to ensure that the calling method should not modify the returned collection.
Since the returned collection is immutable, it provides a performance improvement over using a new instance of a Collection.