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Call to 'set.removeAll(list)' may work slowly

Reports calls to java.util.Set.removeAll() with a java.util.List argument.

Such a call can be slow when the size of the argument is greater than or equal to the size of the set, and the set is a subclass of java.util.AbstractSet. In this case, List.contains() is called for each element in the set, which will perform a linear search.


public void check(String... ss) { // possible O(n^2) complexity mySet.removeAll(List.of(ss)); }

After the quick fix is applied:

public void check(String... ss) { // O(n) complexity List.of(ss).forEach(mySet::remove); }

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New in 2020.3


By default bundled with

IntelliJ IDEA 2024.1, Qodana for JVM 2024.1,

Can be installed with plugin

Java, 241.18072

Last modified: 18 June 2024