Since the introduction of generics in Java 5, the use of generic types such as List<String>
is recommended over the use of raw
ones such as List
. Assigning a raw type to a generic one is not type safe, and will generate a warning. The old EMPTY_...
fields of the Collections
class return raw types, whereas the newer empty...()
methods return generic ones.
List<String> collection1 = Collections.EMPTY_LIST; // Noncompliant Map<String, String> collection2 = Collections.EMPTY_MAP; // Noncompliant Set<String> collection3 = Collections.EMPTY_SET; // Noncompliant
List<String> collection1 = Collections.emptyList(); Map<String, String> collection2 = Collections.emptyMap(); Set<String> collection3 = Collections.emptySet();