Findbugs缺陷等級對照表

1、FindBugsBugDescriptionsThisdocumentliststhestandardbugpatternsreportedbyversion0.8.5.SummaryEC:Calltoequals()comparingdifferent15AinterfacetypesCorrectness調用 Equal 方法去比較不同的接口類型EC:Calltoequals()comparingdifferent16AtypesCorrectness調用 Equal 方法去比較不同的數(shù)據(jù)類型ES:ComparisonofStringobjectsusing=17Ao二使用=或者！=去比較

2、字符串或對象IJU:TestCaseimplementssetUpbutdoesntNP:Nullpointerdereferenceinmethod 方法中存在空指針Nm:Classdefinesequal();shoulditbeC:中定了 equal 方法，但是沒有重寫序號等級DescriptionCategory14AEC:Calltoequals()withnullargument 調用 Equal 方法的參數(shù)為空Correctness29Bcallsuper.setUp()測試實例實現(xiàn)了 setUpsuper.setUp()()但沒有調用CorrectnessCorrectness

3、36ACorrectnessNP:Nullpointerdereferenceinmethodon37Aexceptionpath方法中存在某異常路徑中的空指針NP:Possiblenullpointerdereferencein38Amethod方法中存在可能在運行時出現(xiàn)的空指針異常NP:Possiblenullpointerdereferenceinmethodonexceptionpath39方法中存在可能在某些異常路徑下出現(xiàn)的空指針異常CorrectnessCorrectnessCorrectness41Correctnessjava.lang.Object 中 equal 方法，這也

4、有可能是有意這么做的42Nm:Confusingmethodnames一些方法名只有大小寫的區(qū)別，容易混繞43Nm:Confusingmethodname方法名和其超類的類名相同m:Classdefineshashcode();shoulditbehashCode()?44類中定義了hashCode()方法，但是沒有重寫ava.lang.Object中的hashCode()方法， 這也有可能是有意這么做的Nm:Classdefinestostring();shoulditbetoString()?45類中定義了tostring()方法，但是沒有重寫java.lang.Object中的tostr

5、ing()方法，這也有可能是有意這么做的46Nm:Veryconfusingmethodnames一些方法名只有大小寫的區(qū)別，特別容易混繞47ODR:Methodmayfailtoclosedatabaseresource方法可能沒有關閉數(shù)據(jù)源48ODR:Methodmayfailtoclosedatabaseresourceonexception49方法在異常時可能無法關閉數(shù)據(jù)源OS:Methodmayfailtoclosestream 方法可能沒有關閉流50OS:Methodmayfailtoclosestreamonexception53方法在異常時可能無法關閉流RCN:Redundan

6、tcomparisiontonullofpreviouslycheckedvalue預測值的幾個比較的值中有 null 值54CRCN:Redundantcomparisontonull幾個比較的值中有 null 值57RV:Methodignoresreturnvalue方法忽略了返回值59SI:Staticinitializerforclasscreatesinstancebeforeallstaticfinalfieldsassigned類的靜態(tài)初始化器實例化一個該類對象要在所有的常量屬性定義之前CorrectnessCorrectnessCorrectnessCorrectnessCo

7、rrectnessCorrectnessCorrectnessCorrectnessCorrectnessCorrectnessCorrectnessCorrectnessCorrectness72CUwF:Unwritten 巾 eld永遠不會寫到的字段，所有讀取將返回默認值83MS:Fieldisntfinalbutshouldbe字段應該為常量的卻不是常量Maliciouscodevulnerability86A88A92CIS2:Inconsistentsynchronization類中字段訪問不同步ML:Methodsynchronizesonanupdatedfield 方法從一個

8、可變字段對象的引用中同步。這是不太可能有用的，因為不同的線程可以在不同的對象上同步。Ru:Invokesrunonathread(didyoumeantostartitinstead?)當一個類繼承Runnable接口時候，還去調用 run 方法，實際上只需要調用 Start 方法就可以啟動新的線程，MultithreadedcorrectnessMultithreadedcorrectnessMultithreadedcorrectness93CSC:ConstructorinvokesThread.start()構造函數(shù)調用 Thread.start()Multithreadedcorre

9、ctness102103Dm:MethodinvokesdubiousnewString(String)constructor;justusetheargument方法中調用 String 的構造函數(shù)來新建一個字符用，直接使用其參數(shù)即可Dm:MethodinvokesdubiousString.equals();useString.length()=0instead方法中調用了不確定的 String.equals(),使用String.length()=0 來代替104Dm:MethodinvokestoString()methodonaString;justusetheString方法中用一

10、個字符用去調用方法 toString(),用String 就可以了105Dm:MethodinvokesdubiousnewString()constructor;justuse方法中新建一個空字符串用 newString()。直接用就可以了FI:Emptyfinalizershouldbedeleted106空 finalizer以刪除()方法是沒有用的，所以應該予PerformancePerformancePerformancePerformancePerformance114115C116CUPM:Privatemethodisnevercalled 這個私有方法從來沒有被調用到UrF:

11、Unreadfield讀不到的字段，應該從類中刪除UuF:UnusedfieldPerformancePerformancePerformance讀不到的字段，應該從類中刪除DescriptionsAM:CreatesanemptyjarfileentryThecodecallsputNextEntry(),immediatelyfollowedbyacalltocioseEntry().ThisresultsinanemptyJarFileentry.ThecontentsoftheentryshouldbewrittentotheJarFilebetweenthecallstoputNex

12、tEntry()andcloseEntry().AM:CreatesanemptyzipfileentryThecodecallsputNextEntry(),immediatelyfollowedbyacalltocloseEntry().ThisresultsinanemptyZipFileentry.ThecontentsoftheentryshouldbewrittentotheZipFilebetweenthecallstoputNextEntry()andcloseEntry().BIT:IncompatiblebitmasksThismethodcomparesanexpress

13、ionoftheform(a&C)toD,whichwillalwayscompareunequalduetothespecificvaluesofconstantsCandD.Thismayindicatealogicerrorortypo.BIT:IncompatiblebitmasksThismethodcomparesanexpressionoftheform(a&0)to0,whichwillalwayscompareequal.Thismayindicatealogicerrorortypo.BIT:IncompatiblebitmasksThismethodcom

14、paresanexpressionoftheform(a|C)toD.whichwillalwayscompareunequalduetothespecificvaluesofconstantsCandD.Thismayindicatealogicerrorortypo.Typically,thisbugoccursbecausethecodewantstoperformamembershiptestinabitset,butusesthebitwiseORoperator(|)insteadofbitwiseAND(&).BOA:Classoverridesamethodimplem

15、entedinsuperclassAdapterwronglyThismethodoverridesamethodfoundinaparentclass,wherethatclassisanAdapterthatimplementsalistenerdefinedinthejava.awt.eventorjavax.swing.eventpackage.Asaresult,thismethodwillnotgetcalledwhentheeventoccurs.BRSA:Methodattemptstoaccessaresultsetfieldwithindex0AcalltogetXXXor

16、updateXXXmethodsofaresultsetwasmadewherethefieldindexis0.AsResultSetfieldsstartatindex1,thisisalwaysamistake.CN:ClassimplementsCloneablebutdoesnotdefineoruseclonemethodClassimplementsCloneablebutdoesnotdefineorusetheclonemethod.CN:clonemethoddoesnotcallsuper.clone()Thisclassdefinesaclone()methodthat

17、doesnotcallsuper.clone(),andisnotfinal.Ifthisclass(A)isextendedbyasubclass(B),andthesubclassBcallssuper.clone(),thenitislikelythatBsclone()methodwillreturnanobjectoftypeAwhichviolatesthestandardcontractforclone().Ifallclone()methodscallsuper.clone(),thentheyareguaranteedtouseObject.clone(),whichalwa

18、ysreturnsanobjectofthecorrecttype.Co:CovariantcompareTo()methoddefinedThisclassdefinesacovariantversionofcompareTo().TocorrectlyoverridethecompareTo()methodintheComparableinterface,theparameterofcompareTo()musthavetypejava.lang.Object.DE:MethodmightdropexceptionThismethodmightdropanexception.Ingener

19、al,exceptionsshouldbehandledorreportedinsomeway,ortheyshouldbethrownoutofthemethod.DE:MethodmightignoreexceptionThismethodmightignoreanexception.Ingeneral,exceptionsshouldbehandledorreportedinsomeway,ortheyshouldbethrownoutofthemethod.Dm:MethodinvokesSystem.exit(.)InvokingSystem.exitshutsdowntheenti

20、reJavavirtualmachine.Thisshouldonlybeendonewhenitisappropriate.Suchcallsmakeithardorimpossibleforyourcodetobeinvokedbyothercode.ConsiderthrowingaRuntimeExceptioninstead.EC:Calltoequals()withnullargumentThismethodcallsequals(Object),passinganullvalueastheargument.Accordingtothecontractoftheequals()me

21、thod,thiscallshouldalwaysreturnfalse.EC:Calltoequals()comparingdifferentinterfacetypesThismethodcallsequals(Object)ontworeferencesofunrelatedinterfacetypes(neitherisasubtypeoftheother).Accordingtothecontractofequals(),objectsofdifferentclassesshouldalwayscompareasunequal.Notethatitispossiblethatthep

22、rogramcontainsclassesthatimplementbothinterfaces,sothecomparisonmaybevalid.However,itisworthinspectingclosely.EC:Calltoequals()comparingdifferenttypesThismethodcallsequals(Object)ontworeferencesofdifferenttypes.Accordingtothecontractofequals(),objectsofdifferentclassesshouldalwayscompareasunequal;th

23、erefore,itislikelythattheresultofthiscomparisionwillalwaysbefalseatruntime.ES:ComparisonofStringobjectsusing=or!=Thiscodecomparesjava.lang.Stringobjectsforreferenceequalityusingthe=or!=operators.Unlessbothstringsareeitherconstantsinasourcefile,orhavebeeninternedusingtheSern()method,thesames

24、tringvaluemayberepresentedbytwodifferentStringobjects.Considerusingtheequals(Object)methodinstead.Eq:Covariantequals()methoddefinedThisclassdefinesacovariantversionofequals().Tocorrectlyoverridetheequals。methodinjava.lang.Object,theparameterofequals。musthavetypejava.lang.ObjectEq:Covariantequals()me

25、thoddefined,Object.equals(Object)inheritedThisclassdefinesacovariantversionoftheequals。method,butcallsthenormalequals(Object)methoddefinedinthebasejava.lang.Objectclass.Theclassshouldprobablydefineanon-covariantversionofequals().(I.e.,amethodwiththesignaturebooleanequals(java.lang.Object).FI:Explici

26、tinvocationoffinalizerThismethodcontainsanexplicitinvocationofthefinalize。methodonanobject.Becausefinalizermethodsaresupposedtobeexecutedonce,andonlybytheVM,thisisabadidea.FI:FinalizerdoesnotcallsuperclassfinalizerThisfinalize()methoddoesnotmakeacalltoitssuperclasssfinalize()method.So,anyfinalizerac

27、tionsdefinedforthesuperclasswillnotbeperformed.Addacalltosuper.finalize().FI:FinalizernullifiessuperclassfinalizerThisemptyfinalize。methodexplicitlynegatestheeffectofanyfinalizerdefinedbyitssuperclass.Anyfinalizeractionsdefinedforthesuperclasswillnotbeperformed.Unlessthisisintended,deletethismethod.

28、HE:Classdefinesequals()butnothashCode()Thisclassoverridesequals(Object),butdoesnotoverridehashCode().Therefore,theclassmayviolatetheinvariantthatequalobjectsmusthaveequalhashcodes.HE:Classdefinesequals()andusesObject.hashCode()Thisclassoverridesequals(Object),butdoesnotoverridehashCode(),andinherits

29、theimplementationofhashCode()fromjava.lang.Object(whichreturnstheidentityhashcode,anarbitraryvalueassignedtotheobjectbytheVM).Therefore,theclassisverylikelytoviolatetheinvariantthatequalobjectsmusthaveequalhashcodes.IfyoudontwanttodefineahashCodemethod,and/ordontbelievetheobjectwilleverbeputintoaHas

30、hMap/Hashtable,definethehashCode()methodtothrowUnsupportedOperationExceptionHE:ClassdefineshashCode()butnotequals()ThisclassdefinesahashCode()methodbutnotanequals。method.Therefore,theclassmayviolatetheinvariantthatequalobjectsmusthaveequalhashcodes.HE:ClassdefineshashCode()andusesObject.equals()This

31、classdefinesahashCode()methodbutinheritsitsequals()methodfromjava.lang.Object(whichdefinesequalitybycomparingobjectreferences).Althoughthiswillprobablysatisfythecontractthatequalobjectsmusthaveequalhashcodes,itisprobablynotwhatwasintendedbyoverridingthehashCode()method.(OverridinghashCode()impliesth

32、attheobjectsidentityisbasedoncriteriamorecomplicatedthansimplereferenceequality.)HE:Classinheritsequals()andusesObject.hashCode()Thisclassinheritsequals(Object)fromanabstractsuperclass,andhashCode()fromfromjava.lang.Object(whichreturnstheidentityhashcode,anarbitraryvalueassignedtotheobjectbytheVM).T

33、herefore,theclassisverylikelytoviolatetheinvariantthatequalobjectsmusthaveequalhashcodes.IfyoudontwanttodefineahashCodemethod,and/ordontbelievetheobjectwilleverbeputintoaHashMap/Hashtable,definethehashCode()methodtothrowUnsupportedOperationExceptionIC:InitializationcircularityAcircularitywasdetected

34、inthestaticinitializersofthetwoclassesreferencedbythebuginstance.Manykindsofunexpectedbehaviormayarisefromsuchcircularity.IJU:TestCaseimplementssetUpbutdoesntcallsuper.setUp()ClassisaJUnitTestCaseandimplementsthesetUpmethod.ThesetUpmethodshouldcallsuper.setUp(),butdoesnt.IMSE:DubiouscatchingofIllega

35、lMonitorStateExceptionIllegalMonitorStateExceptionisgenerallyonlythrownincaseofadesignflawinyourcode(callingwaitornotifyonanobjectyoudonotholdalockon).It:Iteratornext()methodcantthrowNoSuchElementexceptionThisclassimplementsthejava.util.Iteratorinterface.However,itsnext()methodisnotcapableofthrowing

36、java.util.NoSuchElementException.Thenext()methodshouldbechangedsoitthrowsNoSuchElementExceptionifiscalledwhentherearenomoreelementstoreturn.MF:ClassdefinesfieldthatobscuresasuperclassfieldThisclassdefinesafieldwiththesamenameasavisibleinstancefieldinasuperclass.Thisisconfusing,andmayindicateanerrori

37、fmethodsupdateoraccessoneofthefieldswhentheywantedtheother.MF:MethoddefinesavariablethatobscuresafieldThismethoddefinesalocalvariablewiththesamenameasafieldinthisclassorasuperclass.Thismaycausethemethodtoreadanuninitializedvaluefromthefield,leavethefielduninitialized,orboth.MWN:Mismatchednotify()Thi

38、smethodcallsObject.notify()orObject.notifyAll()withoutobviouslyholdingalockontheobject.Callingnotify()ornotifyAll()withoutalockheldwillresultinanIllegalMonitorStateExceptionbeingthrown.MWN:Mismatchedwait()ThismethodcallsObject.wait()withoutobviouslyholdingalockontheobject.Callingwait()withoutalockhe

39、ldwillresultinanIllegalMonitorStateExceptionbeingthrown.NP:NullpointerdereferenceinmethodAnullpointerisdereferencedhere.ThiswillleadtoaNullPointerExceptionwhenthecodeisexecuted.NP:NullpointerdereferenceinmethodonexceptionpathApointerwhichisnullonanexceptionpathisdereferencedhere.ThiswillleadtoaNullP

40、ointerExceptionwhenthecodeisexecuted.NotethatbecauseFindBugscurrentlydoesnotpruneinfeasibleexceptionpaths,thismaybeafalsewarning.AlsonotethatFindBugsconsidersthedefaultcaseofaswitchstatementtobeanexceptionpath,sincethedefaultcaseisofteninfeasible.NP:PossiblenullpointerdereferenceinmethodAreferenceva

41、luedereferencedheremightbenullatruntime.ThismayleadtoaNullPointerExceptionwhenthecodeisexecuted.NP:PossiblenullpointerdereferenceinmethodonexceptionpathAreferencevaluewhichisnullonsomeexceptioncontrolpathisdereferencedhere.ThismayleadtoaNullPointerExceptionwhenthecodeisexecuted.NotethatbecauseFindBu

42、gscurrentlydoesnotpruneinfeasibleexceptionpaths,thismaybeafalsewarning.AlsonotethatFindBugsconsidersthedefaultcaseofaswitchstatementtobeanexceptionpath,sincethedefaultcaseisofteninfeasible.NS:Questionableuseofnon-short-circuitlogicThiscodeseemstobeusingnon-short-circuitlogic(e.g.,&or|)ratherthan

43、short-circuitlogic(&or|).Non-short-circuitlogiccausesbothsidesoftheexpressiontobeevaluatedevenwhentheresultcanbeinferredfromknowingtheleft-handside.Thiscanbelessefficientandcanresultinerrorsiftheleft-handsideguardscaseswhenevaluatingtheright-handsidecangenerateanerror.Nm:Classdefinesequal();shou

44、lditbeequals。？Thisclassdefinesamethodequal(Object).Thismethoddoesnotoverridetheequals(Object)methodinjava.lang.Object,whichisprobablywhatwasintended.Nm:ConfusingmethodnamesThereferencedmethodshavenamesthatdifferonlybycapitalization.Nm:ConfusingmethodnameThismethodhasthesamenameasthesuperclassofthecl

45、assitisdefinedin.Nm:Classdefineshashcode();shoulditbehashCode()?Thisclassdefinesamethodcalledhashcode().ThismethoddoesnotoverridethehashCode()methodinjava.lang.Object,whichisprobablywhatwasintended.Nm:Classdefinestostring();shoulditbetoString()?Thisclassdefinesamethodcalledtostring().Thismethoddoesn

46、otoverridethetoString()methodinjava.lang.Object,whichisprobablywhatwasintended.Nm:VeryconfusingmethodnamesThereferencedmethodshavenamesthatdifferonlybycapitalization.ODR:MethodmayfailtoclosedatabaseresourceThemethodcreatesadatabaseresource(suchasadatabaseconnectionorrowset),doesnotassignittoanyfield

47、s,passittoothermethods,orreturnit,anddoesnotappeartoclosetheobjectonallpathsoutofthemethod.Failuretoclosedatabaseresourcesonallpathsoutofamethodmayresultinpoorperformance,andcouldcausetheapplicationtohaveproblemscommunicatingwiththedatabase.ODR:MethodmayfailtoclosedatabaseresourceonexceptionThemetho

48、dcreatesadatabaseresource(suchasadatabaseconnectionorrowset),doesnotassignittoanyfields,passittoothermethods,orreturnit,anddoesnotappeartoclosetheobjectonallexceptionpathsoutofthemethod.Failuretoclosedatabaseresourcesonallpathsoutofamethodmayresultinpoorperformance,andcouldcausetheapplicationtohavep

49、roblemscommunicatingwiththedatabase.OS:MethodmayfailtoclosestreamThemethodcreatesanIOstreamobject,doesnotassignittoanyfields,passittoothermethods,orreturnit,anddoesnotappeartoclosethestreamonallpathsoutofthemethod.Thismayresultinafiledescriptorleak.Itisgenerallyagoodideatouseafinallyblocktoensuretha

50、tstreamsareclosed.OS:MethodmayfailtoclosestreamonexceptionThemethodcreatesanIOstreamobject,doesnotassignittoanyfields,passittoothermethods,orreturnit,anddoesnotappeartocloseitonallpossibleexceptionpathsoutofthemethod.Thismayresultinafiledescriptorleak.Itisgenerallyagoodideatouseafinallyblocktoensure

51、thatstreamsareclosed.PZLA:ConsiderreturningazerolengtharrayratherthannullItisoftenabetterdesigntoreturnalengthzeroarrayratherthananullreferencetoindicatethattherearenoresults(i.e.,anemptylistofresults).Thisway,noexplicitcheckfornullisneededbyclientsofthemethod.Ontheotherhand,usingnulltoindicatethere

52、isnoanswertothisquestion,thenitisprobablyappropriate.Forexample,File.listFiles()returnsanemptylistifgivenadirectorycontainingnofiles,andreturnsnullifthefileisnotadirectory.RC:SuspiciousreferencecomparisonThismethodcomparestworeferencevaluesusingthe=or!=operator,wherethecorrectwaytocompareinstancesof

53、thistypeisgenerallywiththeequals()method.Examplesofclasseswhichshouldgenerallynotbecomparedbyreferencearejava.lang.Integer,java.lang.Float,etc.RCN:RedundantcomparisiontonullofpreviouslycheckedvalueThismethodcontainsaredundantcomparisonofareferencevaluetonull.Twotypesofredundantcomparisonarereported:

54、,BothvaluescomparedaredefinitelynullOnevalueisdefinitelynullandtheotherisdefinitelynotnullThisparticularwarninggenerallyindicatesthatavalueknownnottobenullwascheckedagainstnull.Whilethecheckisnotnecessary,itmaysimplybeacaseofdefensiveprogramming.RCN:RedundantcomparisontonullThismethodcontainsaredund

55、antcomparisonofareferencevaluetonull.Twotypesofredundantcomparisonarereported:BothvaluescomparedaredefinitelynullOnevalueisdefinitelynullandtheotherisdefinitelynotnullThisparticularwarningrepresentstwospecifickindsofredundantcomparisions:1. Avaluewasdereferenced,andlaterexplicitlycomparedtonull:this

56、oftenindicatesanerrorinthemethod2. Aliteralnullvaluewasexplicitlycomparedtonull:thismayindicatethatthemethodwasmodifiedwithoutcompleteunderstandingoftheinvariantsofthemethodRR:MethodignoresresultsofInputStream.read()Thismethodignoresthereturnvalueofoneofthevariantsofjava.io.InputStream.read()whichca

57、nreturnmultiplebytes.Ifthereturnvalueisnotchecked,thecallerwillnotbeabletocorrectlyhandlethecasewherefewerbyteswerereadthanthecallerrequested.Thisisaparticularlyinsidiouskindofbug,becauseinmanyprograms,readsfrominputstreamsusuallydoreadthefullamountofdatarequested,causingtheprogramtofailonlysporadic

58、ally.RR:MethodignoresresultsofInputStream.skip()Thismethodignoresthereturnvalueofjava.io.InputStream.skip()whichcanskipmultiplebytes.Ifthereturnvalueisnotchecked,thecallerwillnotbeabletocorrectlyhandlethecasewherefewerbyteswereskippedthanthecallerrequested.Thisisaparticularlyinsidiouskindofbug,becau

59、seinmanyprograms,skipsfrominputstreamsusuallydoskipthefullamountofdatarequested,causingtheprogramtofailonlysporadically.WithBufferedstreams,however,skip()willonlyskipdatainthebuffer,andwillroutinelyfailtoskiptherequestednumberofbytes.RV:MethodignoresreturnvalueThereturnvalueofthismethodshouldbecheck

60、ed.SA:SelfassignmentoffieldThismethodcontainsaselfassignmentofafield;x;publicvoidfoo()x=x;)Suchassignmentsareuseless,andmayindicatealogicerrorortypo.SI:StaticinitializerforclasscreatesinstancebeforeallstaticfinalfieldsassignedTheclasssstaticinitializercreatesaninstanceoftheclassbeforeallofthestaticfinalfieldsa