Invalid method reference used for 'Comparator'

Reports method references mapped to the Comparator interface that don't fulfill its contract.

Some method references, like Integer::max, can be mapped to the Comparator interface. However, using them as Comparator is meaningless and the result might be unpredictable.

Example:

  ArrayList<Integer> ints = foo();
  ints.sort(Math::min);

After the quick-fix is applied:

  ArrayList<Integer> ints = foo();
  ints.sort(Comparator.reverseOrder());

Locating this inspection

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.

InvalidComparatorMethodReference

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Settings or Preferences | Editor | Inspections | Java | Probable bugs

Inspection Details
By default bundled with:	IntelliJ IDEA 2024.3, Qodana for JVM 2024.3,
Can be installed with plugin:	Java, 243.23126

Last modified: 03 December 2024