Java >> Guava >> Table
Table<Vertex, Vertex, Object> table = HashBasedTable.create();
Vertex column = new Vertex(Type.Column);
Vertex row = new Vertex(Type.Row);
String value = "aValue";
table.put(row, column, value);
List<Vertex> result = new ArrayList<Vertex>();
for (Vertex row : table.rowKeySet())
result.add(row);