(Display shortest paths) Revise GraphView in Listing 28.6 to display a weighted graph and a shortest path between the two specified cities, as shown in Figure 29.19

(Display shortest paths) Revise GraphView in Listing 28.6 to display a weighted graph and a shortest path between the two specified cities, as shown in Figure 29.19. You need to add a data field path in GraphView. If a path is not null, the edges in the path are displayed in red. If a city not in the map is entered, the program displays a text to alert the user.

FIGURE 29.19 WeightedGraph.ShortestPathTree extends AbstractGraph.Tree.