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POScala Case Class equals implementation
 

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  1. POScala Case Class equals implementation
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    <p>Given the following the classes:</p> <pre><code>trait ModelWithId { var id: Long = 0 } case class EntityAttribute ( val entityId: UUID, val attrName: String, val stringVal: Option[String], val boolVal: Option[Boolean], val longVal: Option[Long], val doubleVal: Option[Double], val byteVal: Option[Array[Byte]]) extends ModelWithId{ override def toString() : String = { "EntityAttribute(" + entityId.hashCode + "," + attrName.hashCode + "," + stringVal.map{_.hashCode}.getOrElse(None) + "," + stringVal.hashCode+ "," + boolVal.map{_.hashCode}.getOrElse(None) + "," + boolVal.hashCode+ "," + longVal.map{_.hashCode}.getOrElse(None) + "," + longVal.hashCode+ "," + doubleVal.map{_.hashCode}.getOrElse(None) + "," + doubleVal.hashCode+ "," + byteVal.map{_.hashCode}.getOrElse(None) + ")" } } </code></pre> <p>And the following comparison functions:</p> <pre><code>val newAtttributes : List[EntityAttribute] val withoutIds : List[EntityAttribute] println("without: " + withoutIds) println("new: " + newAtttributes) val differences = newAtttributes.diff(withoutIds) println("diff: " + differences) if(newAtttributes.size == 1 &amp;&amp; withoutIds.size == 1){ println("==: " + (newAtttributes.get(0) == withoutIds.get(0))) println("equals: " + (newAtttributes.get(0).equals(withoutIds.get(0)))) println("hequals: " + (newAtttributes.get(0).hashCode == withoutIds.get(0).hashCode)) } </code></pre> <p>I get the expected difference output 99 out 100 times. Very occasionally the diff function will return an empty list when it should a list of one.</p> <p>Example:</p> <pre><code>without: List(EntityAttribute(428861607,-1147340381,None,120224,None,120224,56,-356863126,None,120224,None)) new: List(EntityAttribute(428861607,-1147340381,None,120224,None,120224,23,424930523,None,120224,None)) diff: List() ==: false equals: false hequals: false </code></pre> <p>I can reliably reproduce this error usually after around 10-18 iterations. The two lists are coming from different sources, so they are being constructed differently. I am guessing that it has something to do with auto-boxing or a bad hashCode implementation but I have been bashing my head into a wall for 2 days without progress.</p> <p>I'm using scala 2.9.0-1.</p>
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    1. USSam Hendley
    1. USSam Hendley
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      1. POScala Case Class equals implementation
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      1. POScala Case Class equals implementation
      1. USDaniel C. Sobral
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    1. COYou could print the actual value, so that we could actually reproduce the problem...
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      1. POScala Case Class equals implementation
      1. USDaniel C. Sobral
    2. COdidn't you forget a `}`after `extends ModelWithId{`?
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      1. POScala Case Class equals implementation
      1. USChristopher Chiche
 

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