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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

By default bundled with:

IntelliJ IDEA 2024.1, Qodana for JVM 2024.1,

Can be installed with plugin:

Java, 241.16690

Last modified: 29 April 2024