Hi Doug:

this is for the next hw:
/proj/adaptive2/course/com1205/f00/hw/2/withDJ-capacity-with-stack

Please can you tell me why I get a null pointer exception.

-- Karl

Demeter/Java version 0.8.1
Copyright (c) 2000 Northeastern University
Reading project file program.prj...
Running the test...
 start new container 
sum 0
 start new container 
sum 1
 start new container 
sum 2
 end container 
sum 3
 total weight 3 but limit is = 1 OVER CAPACITY 
 end container 
sum 4
sum 5
 total weight 6 but limit is = 5 OVER CAPACITY 
 end container 
SUCCESS
done 
DJ start 
The DJ version is: DJ version 0.8.1
The class graph is=============================
java.lang.Object : Item | Item_List | Capacity | Token | java.lang.String | java.lang.Throwable | java.lang.Number | Nonempty_Item_List | java.util.AbstractCollection | SummingVisitor | DifferenceVisitor | CheckingVisitor | UniversalVisitor | Main | edu.neu.ccs.demeter.dj.Visitor | edu.neu.ccs.demeter.Ident | Weight | ParserTokenManager | ASCII_UCodeESC_CharStream | Parser | java.io.Reader | java.lang.StringBuffer | java.io.Writer | java.lang.reflect.AccessibleObject | edu.neu.ccs.demeter.AroundContinuation common .
Item : Container | Simple common extends java.lang.Object.
Container = <contents> Item_List <capacity> Capacity extends Item.
Item_List = <first> Nonempty_Item_List <tail> Nonempty_Item_List extends java.lang.Object implements java.util.Enumeration, java.lang.Cloneable.
java.util.Enumeration : Item_List common .
java.lang.Cloneable : Item_List | java.util.Vector common .
Capacity = <i> java.lang.Integer extends java.lang.Object.
ParseException = <specialConstructor> boolean <currentToken> Token <expectedTokenSequences> int <tokenImage> java.lang.String <eol> java.lang.String extends java.lang.Exception.
boolean = .
Token = <kind> int <beginLine> int <beginColumn> int <endLine> int <endColumn> int <image> java.lang.String <next> Token <specialToken> Token extends java.lang.Object.
int = .
java.lang.String = extends java.lang.Object implements java.io.Serializable, java.lang.Comparable.
java.io.Serializable : java.lang.String | java.lang.Throwable | java.lang.Number | java.util.Vector | edu.neu.ccs.demeter.Ident | java.lang.StringBuffer common .
java.lang.Comparable : java.lang.String | java.lang.Integer common .
java.lang.Exception : ParseException common extends java.lang.Throwable.
java.lang.Throwable : java.lang.Exception | java.lang.Error common <backtrace> java.lang.Object <detailMessage> java.lang.String extends java.lang.Object implements java.io.Serializable.
java.lang.Integer = extends java.lang.Number implements java.lang.Comparable.
java.lang.Number : java.lang.Integer common extends java.lang.Object implements java.io.Serializable.
Nonempty_Item_List = <it> Item <next> Nonempty_Item_List extends java.lang.Object.
DifferenceVisitor = <difference> int <stack> java.util.Stack <sV> SummingVisitor extends java.lang.Object.
java.util.Stack = extends java.util.Vector.
java.util.Vector : java.util.Stack common extends java.util.AbstractList implements java.util.List, java.lang.Cloneable, java.io.Serializable.
java.util.AbstractList : java.util.Vector common extends java.util.AbstractCollection implements java.util.List.
java.util.AbstractCollection : java.util.AbstractList common extends java.lang.Object implements java.util.Collection.
java.util.Collection : java.util.AbstractCollection | java.util.List common <elements> java.lang.Object.
java.util.List : java.util.AbstractList | java.util.Vector common extends java.util.Collection.
SummingVisitor = <total> java.lang.Integer extends java.lang.Object.
CheckingVisitor = <iV> DifferenceVisitor <violations> java.lang.Integer extends java.lang.Object.
UniversalVisitor : PrintVisitor | TraceVisitor | DisplayVisitor | EqualVisitor | SubgraphVisitor | CopyVisitor common extends java.lang.Object.
Main = extends java.lang.Object.
SummingVisitorDJ = <total> int extends edu.neu.ccs.demeter.dj.Visitor.
edu.neu.ccs.demeter.dj.Visitor : SummingVisitorDJ | DifferenceVisitorDJ | CheckingVisitorDJ common extends java.lang.Object.
DifferenceVisitorDJ = <difference> int <stack> java.util.Stack <sV> SummingVisitorDJ extends edu.neu.ccs.demeter.dj.Visitor.
CheckingVisitorDJ = <iV> DifferenceVisitorDJ <violations> int extends edu.neu.ccs.demeter.dj.Visitor.
Simple = <name> edu.neu.ccs.demeter.Ident <w> Weight extends Item.
edu.neu.ccs.demeter.Ident = extends java.lang.Object implements java.io.Serializable.
Weight = <i> java.lang.Integer extends java.lang.Object.
Parser = <token_source> ParserTokenManager <jj_input_stream> ASCII_UCodeESC_CharStream <token> Token <jj_nt> Token <jj_ntk> int <jj_gen> int <jj_expentries> java.util.Vector <jj_expentry> int <jj_kind> int extends java.lang.Object implements ParserConstants.
ParserTokenManager = <input_stream> ASCII_UCodeESC_CharStream <image> java.lang.StringBuffer <jjimageLen> int <lengthOfMatch> int <curChar> char <curLexState> int <defaultLexState> int <jjnewStateCnt> int <jjround> int <jjmatchedPos> int <jjmatchedKind> int extends java.lang.Object implements ParserConstants.
ParserConstants : ParserTokenManager | Parser common .
ASCII_UCodeESC_CharStream = <bufpos> int <bufsize> int <available> int <tokenBegin> int <bufline> int <bufcolumn> int <column> int <line> int <inputStream> java.io.Reader <prevCharIsCR> boolean <prevCharIsLF> boolean <nextCharBuf> char <buffer> char <maxNextCharInd> int <nextCharInd> int <inBuf> int extends java.lang.Object.
java.io.Reader = extends java.lang.Object.
char = .
java.lang.StringBuffer = extends java.lang.Object implements java.io.Serializable.
TokenMgrError = <errorCode> int extends java.lang.Error.
java.lang.Error : TokenMgrError common extends java.lang.Throwable.
PrintVisitor = <indent> int <needSpace> boolean <out> java.io.PrintWriter extends UniversalVisitor.
java.io.PrintWriter = extends java.io.Writer.
java.io.Writer : java.io.PrintWriter common extends java.lang.Object.
TraceVisitor = <indent> int <out> java.io.PrintWriter extends UniversalVisitor.
DisplayVisitor = <indent> int <out> java.io.PrintWriter extends UniversalVisitor.
EqualVisitor = <is_equal> boolean <history> java.util.Stack extends UniversalVisitor.
SubgraphVisitor = <is_equal> boolean <history> java.util.Stack extends UniversalVisitor.
CopyVisitor = <history> java.util.Stack extends UniversalVisitor.
__Subtraversal = <method> java.lang.reflect.Method <object> java.lang.Object <args> java.lang.Object extends edu.neu.ccs.demeter.AroundContinuation.
java.lang.reflect.Method = extends java.lang.reflect.AccessibleObject implements java.lang.reflect.Member.
java.lang.reflect.AccessibleObject : java.lang.reflect.Method common extends java.lang.Object.
java.lang.reflect.Member : java.lang.reflect.Method common .
edu.neu.ccs.demeter.AroundContinuation : __Subtraversal common extends java.lang.Object.
edu.neu.ccs.demeter.dj.Collection = <elements> java.lang.Object.
end class graph =============================

 check container 
begin
Exception in thread "main" java.lang.NullPointerException
	at edu.neu.ccs.demeter.dj.ObjectGraphSlice.traverse(ObjectGraphSlice.java:71)
	at edu.neu.ccs.demeter.dj.TraversalGraph.traverse(TraversalGraph.java:53)
	at Container.checkCapacityDJ(Container.java:64)
	at Main.main(Main.java:37)