所以我的飞行课可能有些不对劲，但我无法弄明白究竟是什么。我正在尝试显示航班信息，但是当我运行时只显示机场（尝试爱丁堡 - >多伦多）。这是我的主要课程：
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.StringTokenizer;
import org.jgrapht.alg.DijkstraShortestPath;
import org.jgrapht.graph.*;
public class FlightItinerary2
{
private static ArrayList<String[]> myEdges;
private static ArrayList<Flight> flight;
public FlightItinerary2()
{
} // ensure non-instantiability.
@SuppressWarnings("resource")
public static void main(String [] args)
{
// create a graph based on Strings
myEdges = new ArrayList<String[]>();
flight = new ArrayList<Flight>();
SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> hrefGraph = createHrefGraph();
// note directed edges are printed as: (<v1>,<v2>)
//printAirports(hrefGraph);
//System.out.println(hrefGraph.toString());
Scanner sc = new Scanner(System.in);
System.out.println("\n Enter 1st airport");
String startVertex = sc.nextLine();
while(!hrefGraph.containsVertex(startVertex))
{
System.err.println("Please enter an existing airport.");
startVertex = sc.nextLine();
}
System.out.println("Enter 2nd airport");
String endVertex = sc.nextLine();
while(!hrefGraph.containsVertex(endVertex))
{
System.err.println("Please enter an existing airport.");
endVertex = sc.nextLine();
}
calculatePath(hrefGraph, startVertex, endVertex);
}
/**
* Creates a directed graph based on Strings that represents link
* structure.
*
* @return a graph based on Strings.
*/
private static SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> createHrefGraph()
{
SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> g =
(SimpleDirectedWeightedGraph<String, DefaultWeightedEdge>) new SimpleDirectedWeightedGraph<String, DefaultWeightedEdge>(DefaultWeightedEdge.class);
{
// add the vertices
g.addVertex("Edinburgh");
g.addVertex("Heathrow");
g.addVertex("Amsterdam");
g.addVertex("Boston");
g.addVertex("Chicago");
g.addVertex("Montreal");
g.addVertex("Toronto");
g.addVertex("New Delhi");
g.addVertex("Shanghai");
g.addVertex("Hong Kong");
// add edges to create linking structure
createTwoWayWeightedEdge(g, "Edinburgh", "Heathrow", 110);
generateFlight("1600", "1800", "BA445", 110);
generateFlight("0400", "0600", "BA452", 110);
createTwoWayWeightedEdge(g, "Heathrow", "Amsterdam", 100);
generateFlight("1400", "1600", "DC123", 100);
generateFlight("0400", "0600", "AB712", 100);
createTwoWayWeightedEdge(g, "Heathrow", "Boston", 230);
generateFlight("1800", "2200", "AD412", 230);
generateFlight("0900", "1300", "AA413", 230);
createTwoWayWeightedEdge(g, "Boston", "Chicago", 150);
generateFlight("0700", "1000", "BA178", 150);
generateFlight("1300", "1600", "YU712", 150);
createTwoWayWeightedEdge(g, "Boston", "Montreal", 100);
generateFlight("1600", "1900", "AG102", 100);
generateFlight("2100", "2300", "AH140", 100);
createTwoWayWeightedEdge(g, "Montreal", "Toronto", 90);
generateFlight("1100", "1200", "AC968", 90);
generateFlight("2000", "2100", "BA360", 90);
createTwoWayWeightedEdge(g, "Edinburgh", "Chicago", 560);
generateFlight("1200", "2000", "BI712", 560);
generateFlight("2100", "0500", "AX023", 560);
createTwoWayWeightedEdge(g, "New Delhi", "Shanghai", 430);
generateFlight("1400", "2000", "AA550", 430);
generateFlight("0600", "1200", "BB102", 430);
createTwoWayWeightedEdge(g, "Shanghai", "Hong Kong", 230);
generateFlight("1400", "1700", "NX450", 230);
generateFlight("2200", "0100", "BL860", 230);
}
return g;
}
private static void createTwoWayWeightedEdge(SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> g, String vertex1, String vertex2, double weight)
{
g.addEdge(vertex1, vertex2);
g.addEdge(vertex2, vertex1);
g.setEdgeWeight(g.getEdge(vertex1, vertex2), weight);
g.setEdgeWeight(g.getEdge(vertex2, vertex1), weight);
String[] tmp1 = {vertex1, vertex2};
myEdges.add(tmp1);
String[] tmp2 = {vertex2, vertex1};
myEdges.add(tmp2);
}
private static void generateFlight(String depTime, String arrTime, String flightNo, double price)
{
Flight f = new Flight(depTime, arrTime, flightNo, price);
flight.add(f);
}
// for displaying flight info nicely
private static String textToPrint(String[] format)
{
String text = " ";
for(int i = 0; i < format.length; i++)
{
switch(i)
{
case 0:
text = text + format[i];
for(int j = format[i].length(); j < 6 ; j++)
text = text + " ";
break;
case 1:
text = text + format[i];
for(int j = format[i].length(); j < 15 ; j++)
text = text + " ";
break;
case 2:
text = text + format[i];
for(int j = format[i].length(); j < 10 ; j++)
text = text + " ";
break;
case 3:
text = text + format[i];
for(int j = format[i].length(); j < 10 ; j++)
text = text + " ";
break;
case 4:
text = text + format[i];
for(int j = format[i].length(); j < 15 ; j++)
text = text + " ";
break;
case 5:
text = text + format[i];
for(int j = format[i].length(); j < 10 ; j++)
text = text + " ";
break;
}
}
return text;
}
@SuppressWarnings({ "rawtypes", "unchecked", "unused" })
private static void calculatePath(SimpleDirectedWeightedGraph<String, DefaultWeightedEdge> g, String startVertex, String endVertex)
{
DijkstraShortestPath path = new DijkstraShortestPath(g, startVertex, endVertex);
path.getPath();
List<Object> edges = path.getPathEdgeList();
String item;
int count = 1;
double totalDuration = 0;
if(edges!=null)
{
System.out.println("\nShortest ( i . e . cheapest ) path :");
String[] labels = {"Leg.", "Leave", "At", "On", "Arrive", "At"};
System.out.println(textToPrint(labels));
for(Object edge : edges)
{
item = edge.toString();
StringTokenizer st = new StringTokenizer(item, ":");
String firstAirport = st.nextToken().trim().substring(1);
String secondAirport = st.nextToken().trim();
secondAirport = secondAirport.substring(0, secondAirport.length()-1);
String depTime = null, arrTime = null, flightNo = null;
double price, flightDuration;
for(int i=0;i<flight.size();i++)
{
if(firstAirport.equals(myEdges.get(i)[0]) && secondAirport.equals(myEdges.get(i)[1]))
{
Flight details = flight.get(i);
flightNo = details.flightNo;
depTime = details.depTime;
arrTime = details.arrTime;
price = details.price;
flightDuration = details.duration;
totalDuration = totalDuration + flightDuration;
String[] tmp = {count+".", firstAirport, depTime, flightNo, secondAirport, arrTime};
System.out.println(textToPrint(tmp));
}
}
count++;
}
System.out.println("Cost of shortest (i.e. cheapest) path = £"+path.getPathLength());
System.out.println("Total time in the air = "+totalDuration+"hrs");
}
else
System.err.println("The path doesn't exist.");
}
}
和Flight.java类：
public class Flight {
String depTime;
String arrTime;
String flightNo;
int duration;
int price;
public Flight(String depTime, String arrTime, String flightNo, double duration){
this.depTime = new String();
this.arrTime = new String();
this.flightNo = new String();
//this.duration = this.getDuration();
}
public int getDuration(){
int duration = Integer.parseInt(arrTime) - Integer.parseInt(depTime);
return duration;
}
public String getFlightNo(){
return flightNo;
}
public double getPrice(){
return price;
}
}
持续时间也不起作用，但这并不重要。谢谢！
答案 0 :(得分：1)
这看起来是您不在变量中存储参数的主要问题。相反，你只是初始化它们。将Flight构造函数更改为如下所示。
public Flight(String depTime, String arrTime, String flightNo, double duration){
this.depTime = depTime;
this.arrTime = arrTime;
this.flightNo = flightNo;
this.duration = duration;
}