'Comparator' combinator can be used

Reports Comparator instances defined as lambda expressions that could be expressed using Comparator.comparing() calls. Chained comparisons which can be replaced by Comparator.thenComparing() expression are also reported.

Example:

  myList.sort((person1, person2) -> person1.getName().compareTo(person2.getName()));

  myList2.sort((person1, person2) -> {
      int res = person1.first().compareTo(person2.first());
      if(res == 0) res = person1.second().compareTo(person2.second());
      if(res == 0) res = person1.third() - person2.third();
      return res;
  });

After the quick-fixes are applied:

  myList.sort(Comparator.comparing(Person::getName));

  myList2.sort(Comparator.comparing(Person::first)
                         .thenComparing(Person::second)
                         .thenComparingInt(Person::third));

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.

ComparatorCombinators

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.

This inspection depends on the Java feature 'Lambda expressions', which is available since Java 8.

Inspection Details
By default bundled with:	IntelliJ IDEA 2024.3, Qodana for JVM 2024.3,
Can be installed with plugin:	Java, 243.26483

01 April 2025