toString on Array

ID

kotlin.tostring_on_array

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Reliability

Language

Kotlin

Tags

array, reliability

Description

Reports calls to toString() on an array type.

Arrays in Kotlin (and Java) inherit toString() from Object, which returns an address-like string such as [I@1b6d3586 — the internal type descriptor followed by the identity hash code. This string carries no information about the array’s elements and is almost never what was intended.

Rationale

val a = intArrayOf(1, 2, 3)

println(a.toString())          // FLAW — prints "[I@1b6d3586"

println(a.contentToString())   // OK — prints "[1, 2, 3]"

Remediation

Replace toString() on arrays with the appropriate content-aware alternative:

  • Use contentToString() for single-dimensional arrays.

  • Use contentDeepToString() for nested (multi-dimensional) arrays.

References