Immutable collection creation can be replaced with collection factory call
Reports java.util.Collections
unmodifiable collection calls that can be converted to newer collection factory methods. These can be replaced with e.g. List.of()
or Set.of()
introduced in Java 9 or List.copyOf()
introduced in Java 10.
Note that in contrast to java.util.Collections
methods, Java 9 collection factory methods:
Do not accept
null
values.Require unique set elements and map keys.
Do not accept
null
arguments to query methods likeList.contains()
orMap.get()
of the collections returned.
When these cases are violated, exceptions are thrown. This can change the semantics of the code after the migration.
Example:
List<Integer> even = Collections.unmodifiableList(
Arrays.asList(2, 4, 6, 8, 10, 2));
List<Integer> evenCopy = Collections.unmodifiableList(
new ArrayList<>(list1));
After the quick-fix is applied:
List<Integer> even = List.of(2, 4, 6, 8, 10, 2);
List<Integer> evenCopy = List.copyOf(list);
- By ID
Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.
Java9CollectionFactory
Use the Do not warn when content is non-constant option to report only in cases when the supplied arguments are compile-time constants. This reduces the chances that the behavior changes, because it's not always possible to statically check whether original elements are unique and not null
.
Use the Suggest 'Map.ofEntries' option to suggest replacing unmodifiable maps with more than 10 entries with Map.ofEntries()
.
This inspection depends on the Java feature 'Collection factory methods', which is available since Java 9.
New in 2017.2
Here you can find the description of settings available for the Immutable collection creation can be replaced with collection factory call inspection, and the reference of their default values.
Inspection Details | |
---|---|
By default bundled with: | |
Can be installed with plugin: | Java, 243.23126 |
Thanks for your feedback!