Modify GraphView in Listing 28.6 to add a new data field tree with a set method. The edges in the tree are displayed in red. Write a program that displays the graph in Figure 28.1 and the DFS/BFS tree starting from a specified city, as shown in Figures 28.13 and 28.16. If a city not in the map is entered, the program displays an error message in the label.

Listing

1 import javafx.scene.layout.Pane; 2 import javafx.scene.shape.Circle; 3 import javafx.scene.shape.Line; 4 import javafx.scene.text.Text; 5 6 public class GraphView extends Pane { private Graph