Constant conditions

Reports non-trivial conditions and values that are statically known to be always true, false, null or zero. While sometimes intended, often this is a sign of logical error in the program. Additionally, reports never reachable when branches and some expressions that are statically known to fail always.

Examples:

fun process(x: Int?) {
  val isNull = x == null
  if (!isNull) {
    if (x != null) {} // condition is always true
    require(x!! < 0 && x > 10) // condition is always false
  } else {
    println(x!!) // !! operator will always fail
  }
}
fun process(v: Any) {
  when(v) {
    is CharSequence -> println(v as Int) // cast will always fail
    is String -> println(v) // branch is unreachable
  }
}

Uncheck the "Warn when constant is stored in variable" option to avoid reporting of variables having constant values not in conditions.

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.

KotlinConstantConditions

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

New in 2021.3

Inspection options

Here you can find the description of settings available for the Constant conditions inspection, and the reference of their default values.

Warn when constant is stored in variable: Default: Selected

Availability

By default bundled with: IntelliJ IDEA 2024.1, Qodana for JVM 2024.1,
Can be installed with plugin: Kotlin, 241.18072-IJ

Last modified: 18 June 2024