Error in hashtable mapping

Question

hi all,
in the following code, I get an error in the "find()" method in
this statement
comparedURL = (Document)ht.get(findElement);
It gives me a null ptr exception..
any ideas...?
Here is the code
static void compareDocuments ( Hashtable ht )
Enumeration keys = ht.keys();
Document doc = null;
String findElement = "";
try
while ( keys.hasMoreElements())
doc = (Document ) ht.get(keys.nextEleme());
for(int h=0;h<doc.getOutgoingLinks().size();h++)
findElement = (String)doc.getOutgoingLinks.elementAt(h));
find ( ht,doc,findElement);
catch ( .... )
static void find ( Hashtable ht, Document d, String findElement)
Enumeration keys = ht.keys();
Document comparedURL = null;
double incomingWeight = 0.0;
System.out.println(findElement);
try
comparedURL = (Document)ht.get(findElement);
comparedURL.incomingWeight = d.getOutgoingCount();
comparedURL.rank+= (d.rank/comparedURL.incomingWeight);
catch ( NullPointerException npe )
npe.printStackTrace();

Answer 1

Well, could you show us that output? And please show
one of the keys that you are passing to the get method
as well.This is what the hashtable contains
http://www.bnet.att.com:80/leadstories/96-10-16/recentletters.htm,1.0
http://www.brabys.co.za:80/caversham/botswana/Tati.htm,1.0
http://www.brazzil.com:80/aug93.htm,1.0
http://www.brabys.co.za:80/caversham/botswana/first.htm,1.0
http://www.bnet.att.com:80/leadstories/96-10-17/recentletters.htm,1.0
http://www.bnet.att.com:80/leadstories/96-10-17/bookmark.htm,1.0
http://www.brazzil.com:80/oct93.htm,1.0
http://www.brazzil.com:80/sep93.htm,1.0
http://www.atr.org:80/townhall/FRC/net/st96e5.html,1.0
http://www.brabys.co.za:80/caversham/wcape/Tourism.htm,1.0
the hash function is
doc = new Document(
docNo,header,incomingVector,ogVector, incomingCount,outgoingCount,incomingWeight,
outgoingWeight,rank);
hash function
ht.put(header,doc)