Throwing Same Exception

ID

kotlin.throwing_same_exception

Severity

low

Remediation Complexity

medium

Remediation Risk

low

Remediation Effort

medium

Resource

Code Smell

Language

Kotlin

Tags

catch, exception, stack-trace

Description

Reports catch (e: X) { …​ throw X(…​) …​ } patterns where the catch body constructs and throws a brand-new instance of the same declared exception type without passing the caught exception e as a cause. The original cause and stack trace are lost.

Rationale

// Bad — cause discarded
try { ... } catch (e: IOException) {
    throw IOException("retrying failed")            // FLAW
}

// OK — original cause is preserved
try { ... } catch (e: IOException) {
    throw IOException("retrying failed", e)
}

// OK — different exception type
try { ... } catch (e: IOException) {
    throw IllegalStateException("wrapped", e)
}

// OK — bare rethrow (handled by kotlin.rethrow_caught_exception)
try { ... } catch (e: IOException) {
    throw e
}

A new exception of the same type effectively re-throws but drops the inner stack trace, so the diagnostic value of the catch is negative.

Remediation

  • Pass the caught exception as the cause argument: throw X("msg", e).

  • Use a bare rethrow when no additional context is needed: throw e.

  • If the catch performs work and then rethrows, log the original exception with the catch parameter rather than constructing a new instance.

References