KT.USE_CHECK_OR_ERROR

Invariant check throws an IllegalStateException

Kotlin provides a concise way to check invariants as well as pre- and post-conditions. Prefer them instead of manually throwing an IllegalStateException.

Noncompliant Code

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if (value == null) throw IllegalStateException("value should not be null")
if (value < 0) throw IllegalStateException("value is $value but should be at least 0")
when(a) {
    1 -> doSomething()
    else -> throw IllegalStateException("Unexpected value")
}

Compliant Code

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checkNotNull(value) { "value should not be null" }
check(value >= 0) { "value is $value but should be at least 0" }
when(a) {
    1 -> doSomething()
    else -> error("Unexpected value")
}