JDK-8057793 : BigDecimal is no longer effectively immutable
  • Type: Bug
  • Component: core-libs
  • Sub-Component: java.math
  • Affected Version: 8u11
  • Priority: P3
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2014-09-03
  • Updated: 2015-11-05
  • Resolved: 2014-09-15
The Version table provides details related to the release that this issue/RFE will be addressed.

Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.

To download the current JDK release, click here.
JDK 8 JDK 9
8u40Fixed 9 b32Fixed
Description
FULL PRODUCT VERSION :
java version "1.8.0_20"
Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)


A DESCRIPTION OF THE PROBLEM :
Calling BigDecimal.setScale now changes the underlying object sometimes. It is unclear under which conditions the bug manifests itself.

REGRESSION.  Last worked in version 7u67

ADDITIONAL REGRESSION INFORMATION: 
java version "1.8.0_20"
Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the attached code. It should 

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The program should print "Success!"
ACTUAL -
It throws an Exception

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package ponder;

import java.math.BigDecimal;
import java.math.RoundingMode;

public class Bug
{
	public static void main (String[] args) throws Exception
	{
		BigDecimal total = new BigDecimal ("258815507198903607775511093103396443816569106750031264155319238473795838680758514810110764742309284477206138527975952150289602995045050194333030191178778772026538699925775139201970526695485362661420908248887297829319881475178467494779683293036572059595504702727301324759997409522995072582369210284334718757260859794972695026582432867589093687280300148141501712013226636373167978223780290547640482160818746599330924736802844173226042389174403401903999447463440670236056324929325189403433689" +
			".426167432065785331444814035799717606745777287606858873045971898862329763544687891847664736523584843544347118836628373041412918374550458884706686730726101338872517021688769782894793734049819222924171842793485919753186993388451909096042127903835765393729547730953942175461146061715108701615615142134282261293656760570061554783195726716403304101469782303957325142638493327692352838806741611887655695029948975509680496573999174402058593454203190963443179532640446352828089016874853634851387762579319853267317320515941105912189838719919259277721994880193541634872882180184303434360412344059435559680494807415573269199203376126242271766939666939316648575065702750502798973418978204972336924254702551350654650573582614211506856383897692911422458286912085339575875324832979140870119455620532272318122103640233069115700020760625493816902806241630788230268031695140687964931377988962507263990468276009750998066442971308866347136022907166625330623130307555914930120150437900510530537258665172619821272937026713977709974434967165159545592482710663639966781678268622620229577009317698254134914742098420792313931843709810905414336383757407675429663714210967924767434203021205270369316797752411974617662200898086335322218191674846795163102021505555508444216708745911194321674887527227200297039471799580744303346354057273540730643842091810899490590914195225087593013834388801018488174855060306804024894292757613618190472234110859436472645203753139820658279559340251226992556744343475086923568365637919479462424794554522865559888240039662899509652221329892034706445253487898044421278283079233226845124525434586324657471286953226255430662125870993375281512713207125720748163498642795960457639954616530163959004770092547297392499137383176609646505351001304840762905826237024982330597805063521162285806541220110524989649256399233792799406995068469271941269511818994954109392839548141262324660472253632382325038836831429045617036015122388070240133760858500132713255407855625837956886349324981003917084922808187223285051144454915441134217743066575863563572152133978905444998209075763950909784148142018992367290485890072303179512881131769414783097454103103347826517701720263541869335631166977965013552647906729408522950996105479525445916501155305220090853891226367184989434453290788068397817927893708837722255115237672194162924260945492012622891770365546831236789867922136747819364833843397165107825773447549885351449899330007200651144003961228091210630807333236718793283427788965479074476288255387824982443633190938302785760754436525586544523339170400053128503337395428393881357669568532722167493096151221381017320147344991331421789379785964440840684363041795410525097564979585773948558651896834067324427900848255265001498890329859444233861478388742393060996236783742654761350763876989363052609107226398858310051497856931093693697981165801539060516895227818925342535261227134364063673285588256280386915163875872231395348293505967057794409379709079685798908660258077792158532257603211711587587586356431658240229896344639704");
		if (total.setScale (0, RoundingMode.DOWN).equals (total.setScale (0, RoundingMode.DOWN)))
		{
			System.out.println ("Success!");
		} else
		{
			throw new Exception ("Fail :(");
		}
	}
}
---------- END SOURCE ----------
Comments
See the core-libs thread: http://mail.openjdk.java.net/pipermail/core-libs-dev/2014-September/028569.html
11-09-2014
Bug is reproducible on 8u11 Macintosh, i.e., it throws an exception, because the result of equals() is false. The test passes, i.e., prints "Success!" when run on 7u45 Macintosh. Inserting BigDecimal temp = total.setScale(0, RoundingMode.DOWN); before the if-statement changes the behavior so that the test prints "Success!" on 8u11. Clearly this statement has some side effect on 'total' that is visible to the equals() method.
08-09-2014