[jgrapht-users] graph object instantiation.

[Balaji I. <bri...@gm...>]

Hello, 
 
I have a DefaultDirectedGraph object as a private member of a class,
which i instantiate in the constructor of the class. I then use call
the addVertex function later from other files in my code structure.
This is how my class looks like:
 
class SampleGraph { 
private DefaultDirectedGraph g_graph; 
// other members 
 
// constructor 
SampleGraph(){  
DefaultDirectedGraph g_graph = new DefaultDirectedGraph(); 
} 
 
// wrapper method 
protected final boolean addNode(Object gnode){ 
return g_graph.addVertex(gnode); 
}  
} 
 
elsewhere in the code i do: 
 
SampleGraph tmp-graph-obj = new SampleGraph (); 
tmp-obj.addVertex(tmp-node); 
 
which should add the tmp-node to the g_graph member of tmp-graph-obj,
is this the right way of doing this. I get a null pointer exception
here and i cant figure what i am doing wrong here.
Any help would be very much appreciated. 
 
thanks