# Declaring java-interface on data class breaks "equals"

**URL:** <https://discuss.kotlinlang.org/t/declaring-java-interface-on-data-class-breaks-equals/451>\
**Category:** Uncategorized\
**Created:** [October 1, 2014, 5:36am UTC](https://discuss.kotlinlang.org/t/declaring-java-interface-on-data-class-breaks-equals/451 "2014-10-01T05:36:46Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Unitcraft](https://avatars.discourse-cdn.com/v4/letter/u/2acd7d/32.png) [@Unitcraft](https://discuss.kotlinlang.org/u/Unitcraft)\
**Post date:** [October 1, 2014, 5:36am UTC](https://discuss.kotlinlang.org/t/declaring-java-interface-on-data-class-breaks-equals/451/1 "2014-10-01T05:36:46Z")

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This test fails:

```kotlin
class TestRes{
    Test fun eqName(){
        assertEquals(Name("a"),Name("a"))
    }
}

data class Name(val name:String): Runnable{ // or any java interface
  override fun run() {
  throw UnsupportedOperationException()
  }
}
```

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<div class="post-metadata">

**Author:** ![abreslav](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/abreslav/32/8279_2.png) [@abreslav](https://discuss.kotlinlang.org/u/abreslav)\
**Post date:** [October 1, 2014, 12:32pm UTC](https://discuss.kotlinlang.org/t/declaring-java-interface-on-data-class-breaks-equals/451/2 "2014-10-01T12:32:42Z")

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Should be fixed in the recent builds, AFAIK. What version of Kotlin are you using?

---

<div class="post-metadata">

**Author:** ![Unitcraft](https://avatars.discourse-cdn.com/v4/letter/u/2acd7d/32.png) [@Unitcraft](https://discuss.kotlinlang.org/u/Unitcraft)\
**Post date:** [October 1, 2014, 5:58pm UTC](https://discuss.kotlinlang.org/t/declaring-java-interface-on-data-class-breaks-equals/451/3 "2014-10-01T17:58:43Z")

</div>

0.8.11.1

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<div class="post-metadata">

**Author:** ![abreslav](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/abreslav/32/8279_2.png) [@abreslav](https://discuss.kotlinlang.org/u/abreslav)\
**Post date:** [October 1, 2014, 6:08pm UTC](https://discuss.kotlinlang.org/t/declaring-java-interface-on-data-class-breaks-equals/451/4 "2014-10-01T18:08:23Z")

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You can use our bleeding edge builds for now, or wait until we roll out M9 (very soon)