Collection count can be converted to size

Reports calls to Collection<T>.count().

This function call can be replaced with .size.

.size form ensures that the operation is O(1) and won't allocate extra objects, whereas count() could be confused with Iterable<T>.count(), which is O(n) and allocating.

Example:

  fun foo() {
      var list = listOf(1,2,3)
      list.count() // replaceable 'count()'
  }

After the quick-fix is applied:

  fun foo() {
      var list = listOf(1,2,3)
      list.size
  }

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.

ReplaceCollectionCountWithSize

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 | Kotlin | Style issues

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

01 April 2025