Negated boolean expression can be simplified

Reports negated boolean expressions that can be simplified.

The quick-fix simplifies the boolean expression.

Example:

    fun test(n: Int) {
        !(0 == 1)
    }

After the quick-fix is applied:

    fun test(n: Int) {
        0 != 1
    }

Please note that this action may change code semantics if IEEE-754 NaN values are involved:

    fun main() {
        println(!(Double.NaN >= 0)) // true
    }

After the quick-fix is applied:

    fun main() {
        println(Double.NaN < 0) // false
    }

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.

SimplifyNegatedBinaryExpression

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