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hashCode of a ju.MapWrapper containing a null value throws a NullPointerException #8504

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scabug opened this issue Apr 15, 2014 · 2 comments
Closed

hashCode of a ju.MapWrapper containing a null value throws a NullPointerException #8504

scabug opened this issue Apr 15, 2014 · 2 comments
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@gourlaysama
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2.11.1

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@scabug
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scabug commented Apr 15, 2014

Calling hashCode on a java map wrapper fails, because hashCode in Wrappers.scala (line 190) calls v.hashCode without checking for null. This seems unexpected since calling hashCode on a scala map works fine even if it contains a null value (and I believe the same goes for java).

It also breaks some iteration constructs; for example, calling .zipWithIndex on a wrapped map containing a wrapped map that has a null value throws a NullPointerException

Here's a stack trace/how to reproduce:

Simple case:

❯ scala                                                                                                                                                              1 ↵
Welcome to Scala version 2.10.2 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_40).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import scala.collection.JavaConversions._
import scala.collection.JavaConversions._

scala> val scalaMap = Map(1 -> null)
scalaMap: scala.collection.immutable.Map[Int,Null] = Map(1 -> null)

scala> val javaMap = mapAsJavaMap(scalaMap)
javaMap: java.util.Map[Int,Null] = {1=null}

scala> scalaMap.hashCode
res0: Int = 1600778741

scala> javaMap.hashCode
java.lang.NullPointerException
	at scala.collection.convert.Wrappers$MapWrapper$$anon$1$$anon$5$$anon$6.hashCode(Wrappers.scala:190)
	at java.util.AbstractMap.hashCode(AbstractMap.java:494)
	at .<init>(<console>:13)
	at .<clinit>(<console>)
	at .<init>(<console>:7)
	at .<clinit>(<console>)
	at $print(<console>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:734)
	at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:983)
	at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:573)
	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:604)
	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:568)
	at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:745)
	at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:790)
	at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:702)
	at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:566)
	at scala.tools.nsc.interpreter.ILoop.innerLoop$1(ILoop.scala:573)
	at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:576)
	at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:867)
	at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822)
	at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822)
	at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135)
	at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822)
	at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:83)
	at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:96)
	at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:105)
	at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

Case where zipWithIndex breaks:

scala> val javaMap2 = mapAsJavaMap(Map(1 -> 2, 3 -> mapAsJavaMap(Map(4 -> null))))
javaMap2: java.util.Map[Int,Any] = {1=2, 3={4=null}}

scala> javaMap2.zipWithIndex
java.lang.NullPointerException
	at scala.collection.convert.Wrappers$MapWrapper$$anon$1$$anon$5$$anon$6.hashCode(Wrappers.scala:190)
	at java.util.AbstractMap.hashCode(AbstractMap.java:494)
	at scala.runtime.ScalaRunTime$.hash(ScalaRunTime.scala:214)
	at scala.util.hashing.MurmurHash3.productHash(MurmurHash3.scala:63)
	at scala.util.hashing.MurmurHash3$.productHash(MurmurHash3.scala:210)
	at scala.runtime.ScalaRunTime$._hashCode(ScalaRunTime.scala:176)
	at scala.Tuple2.hashCode(Tuple2.scala:19)
	at scala.runtime.ScalaRunTime$.hash(ScalaRunTime.scala:214)
	at scala.collection.mutable.HashTable$HashUtils$class.elemHashCode(HashTable.scala:398)
	at scala.collection.mutable.HashMap.elemHashCode(HashMap.scala:39)
	at scala.collection.mutable.HashTable$class.findOrAddEntry(HashTable.scala:161)
	at scala.collection.mutable.HashMap.findOrAddEntry(HashMap.scala:39)
	at scala.collection.mutable.HashMap.$plus$eq(HashMap.scala:89)
	at scala.collection.mutable.HashMap.$plus$eq(HashMap.scala:39)
	at scala.collection.IterableLike$$anonfun$zipWithIndex$1.apply(IterableLike.scala:268)
	at scala.collection.IterableLike$$anonfun$zipWithIndex$1.apply(IterableLike.scala:267)
	at scala.collection.Iterator$class.foreach(Iterator.scala:727)
	at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
	at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
	at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
	at scala.collection.IterableLike$class.zipWithIndex(IterableLike.scala:267)
	at scala.collection.AbstractIterable.zipWithIndex(Iterable.scala:54)
	at .<init>(<console>:12)
	at .<clinit>(<console>)
	at .<init>(<console>:7)
	at .<clinit>(<console>)
	at $print(<console>)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:734)
	at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:983)
	at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:573)
	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:604)
	at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:568)
	at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:745)
	at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:790)
	at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:702)
	at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:566)
	at scala.tools.nsc.interpreter.ILoop.innerLoop$1(ILoop.scala:573)
	at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:576)
	at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:867)
	at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822)
	at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822)
	at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135)
	at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822)
	at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:83)
	at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:96)
	at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:105)
	at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
@scabug
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scabug commented Apr 15, 2014

Imported From: https://issues.scala-lang.org/browse/SI-8504?orig=1
Reporter: Ilya Brin (ibrin)
Affected Versions: 2.10.2

@scabug
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scabug commented Apr 29, 2014

@gourlaysama said:
PR: scala/scala#3704

@scabug scabug closed this as completed May 8, 2014
@scabug scabug added this to the 2.11.1 milestone Apr 7, 2017
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