'toString()' called on array

Calling toString() on an array returns the address of the object in memory, not a string representation of the array's contents. This is almost never what you want.

To get a string representation of an array correctly, use:

contentToString() for linear arrays
contentDeepToString() for multidimensional arrays

Example (explicit toString):

  fun main() {
      val a = arrayOf(1, 2, 3)
      val s = a.toString() // incorrect
  }

  fun main() {
      val a = arrayOf(1, 2, 3)
      val s = a.contentToString() // correct
  }

Example (implicit toString in string template):

  fun main() {
      val a = arrayOf(1, 2, 3)
      println("Array: $a") // incorrect - prints address
  }

  fun main() {
      val a = arrayOf(1, 2, 3)
      println("Array: ${a.contentToString()}") // correct - prints [1, 2, 3]
  }

Example (multidimensional array):

  fun main() {
      val a2d = arrayOf(arrayOf(1, 2), arrayOf(3, 4))
      val s = a2d.toString() // incorrect
  }

  fun main() {
      val a2d = arrayOf(arrayOf(1, 2), arrayOf(3, 4))
      val s = a2d.contentDeepToString() // correct - prints [[1, 2], [3, 4]]
  }

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.

KotlinArrayToString

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

Inspection ID: KotlinArrayToString

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection KotlinArrayToString

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2026.1

Inspection Details
By default bundled with:	IntelliJ IDEA 2026.1, Qodana for JVM 2026.1,

Last modified: 31 March 2026