Useless call on collection type

Reports filter… calls from the standard library on already filtered collections.

Several functions from the standard library such as filterNotNull() or filterIsInstance have sense only when they are called on receivers that have types distinct from the resulting one. Otherwise, such calls can be omitted as the result will be the same.

Remove redundant call quick-fix can be used to amend the code automatically.

Example:

  fun test(list: List<String>) {
      val x = list.filterNotNull() // quick-fix simplifies to 'list'
      val y = list.filterIsInstance<String>() // quick-fix simplifies to 'list'
  }

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.

UselessCallOnCollection

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 | Probable bugs

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

Last modified: 03 December 2024