'equals()' and 'hashCode()' not paired

Reports classes that override equals() but do not override hashCode(), or vice versa. It also reports object declarations that override either equals() or hashCode().

This can lead to undesired behavior when a class is added to a Collection

Example:

  class C1 {
      override fun equals(other: Any?) = true
  }

  class C2 {
      override fun hashCode() = 0
  }

  object O1 {
      override fun equals(other: Any?) = true
  }

  object O2 {
      override fun hashCode() = 0
  }

The quick-fix overrides equals() or hashCode() for classes and deletes these methods for objects:

   class C1 {
       override fun equals(other: Any?) = true
       override fun hashCode(): Int {
           return javaClass.hashCode()
       }
   }

   class C2 {
       override fun hashCode() = 0
       override fun equals(other: Any?): Boolean {
           if (this === other) return true
           if (javaClass != other?.javaClass) return false
           return true
       }
   }

   object O1 {
   }

   object O2 {
   }

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.

EqualsOrHashCode

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 Details
By default bundled with:	IntelliJ IDEA 2024.3, Qodana for JVM 2024.3,
Can be installed with plugin:	Kotlin, 243.23126-IJ

Last modified: 03 December 2024