Call to 'list.containsAll(collection)' may have poor performance

Reports calls to containsAll() on java.util.List.

The time complexity of this method call is O(n·m), where n is the number of elements in the list on which the method is called, and m is the number of elements in the collection passed to the method as a parameter. When the list is large, this can be an expensive operation.

The quick-fix wraps the list in new java.util.HashSet<>() since the time required to create java.util.HashSet from java.util.List and execute containsAll() on java.util.HashSet is O(n+m).

Example:

public boolean check(List<String> list, Collection<String> collection) {
  // O(n·m) complexity
  return list.containsAll(collection);
}

After the quick-fix is applied:

public boolean check(List<String> list, Collection<String> collection) {
  // O(n+m) complexity
  return new HashSet<>(list).containsAll(collection);
}

New in 2022.1

Inspection Details
Available in:	IntelliJ IDEA 2023.3, Qodana for JVM 2023.3
Plugin:	Java, 233.SNAPSHOT

Last modified: 13 July 2023