java - Simple undirected unlabelled graph in JGraphT doesn't work? What is the edgeClass parameter? -


i want make simple undirected unlabelled (edges aren't labelled) graph a<->b in jgrapht 0.8.3:

import org.jgrapht.graph.defaultedge; import org.jgrapht.graph.simplegraph;  class {     public static void main(string[] args) {         simplegraph<string, string> sg =             new simplegraph<string, string>(string.class);         sg.addvertex("a");         sg.addvertex("b");         sg.addedge("a", "b");         system.out.println("edges of a: " + sg.edgesof("a"));         system.out.println("edges of b: " + sg.edgesof("b"));     } } 

i output:

$ java -cp 'jgrapht-jdk1.6.jar:.' edges of a: [] edges of b: [] 

why sets of edges of vertices a , b empty? class parameter of simplegraph for? seems type of edges, since edges here unlabelled, surely doesn't matter? graph classes seem take class of edge (edgeclass) parameter. can't find in documentation edgeclass described.


i found if label edge (change addedge line sg.addedge("a", "b", "an_edge");) works... don't want label edges...

$ java -cp 'jgrapht-jdk1.6.jar:.' edges of a: [an_edge] edges of b: [an_edge] 

you don't have label edges. problem in approach tell graph use string edge type. proper std. way of doing things be:

    simplegraph<string, defaultedge> sg = new simplegraph<string, defaultedge>(defaultedge.class);     sg.addvertex("a");     sg.addvertex("b");     sg.addvertex("c");     sg.addedge("a", "b");     sg.addedge("b", "c");     system.out.println("graph: " + sg.tostring());     system.out.println("edges of a: " + sg.edgesof("a"));     system.out.println("edges of b: " + sg.edgesof("b")); 

this give following output:

graph: ([a, b, c], [{a,b}, {b,c}]) edges of a: [(a : b)] edges of b: [(a : b), (b : c)] 

so fix problem necessary switch edge class defaultedge shown in code.


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