無法打印陣列列表

Question

我無法打印getLines方法，我在這裏做錯了什麼？它不會給我任何錯誤，當我運行該程序，但是當我嘗試打印getlines方法時，它給我錯誤。

當我嘗試打印getlines方法時，它給了我這個錯誤。 異常在線程 「主」 java.lang.ArrayIndexOutOfBoundsException：在dijkstra.Fileprocess.getLines 1（Fileprocess.java:37）在dijkstra.Fileprocess.main（Fileprocess.java:70）

 public class Fileprocess { 


    public static Scanner Reader(String FileName){ 

     //Pass a File Name to this method, then will return Scanner for reading data from that file 
     try { 
      return new Scanner(new File(FileName)); 
     } catch (FileNotFoundException ex) { 
      ex.printStackTrace(); 
      System.exit(1); 
      return null; 
     } 
    } 
    static ArrayList<Edge> getLines(ArrayList<Vertex> PointCollection) { 
     Scanner Input = Reader(Vertex.graph); 
     ArrayList<Edge> result = new ArrayList<Edge>(); 

     while(Input.hasNext()){ 
      String line = Input.nextLine(); 

      String[] arr = line.split(" "); 
      result.add(new Edge(Integer.parseInt(arr[0]), //index 
        getPointbyIndex(PointCollection,Integer.parseInt(arr[1])), //start 
        getPointbyIndex(PointCollection,Integer.parseInt(arr[2])), //end 
        Integer.parseInt(arr[3]))); //cost 
      } 
     Input.close(); 
     return result; 
    } 

    static ArrayList<Vertex> getPoints() { 
     Scanner Input = Reader(Vertex.airports); 
     ArrayList<Vertex> result = new ArrayList<Vertex>(); 

     while(Input.hasNext()){ 
      String line = Input.nextLine(); 
      result.add(new Vertex(line)); 
     } 
     Input.close(); 
     return result; 
    } 

    static Vertex getPointbyIndex(ArrayList<Vertex>PointCollection, int Index){ 
     for(Vertex p:PointCollection){ 
      if(p.getIndex() == Index){ 
       return p; 
      } 
     } 
     return null; 
    } 

public static void main(String[] args){ 
    System.out.println(getPoints()); 
    System.out.println(getLines(null)); 
    } 


} 

這是文件對輸入文本文件（索引，起點，終點，成本）

1 1 2 2 
2 1 3 1 
3 1 6 3 
4 1 7 3 
5 2 1 2 
6 2 3 1 
7 2 4 1 
8 2 5 2 
9 2 6 2 
10 3 1 1 
11 3 2 1 
12 3 4 1 


class Edge { 

    public Vertex start; 
    public Vertex end; 
    public double cost; 
    public int Index; 

// public final Vertex target; 
// public final int weight; 


    public Edge(double cost, Vertex end, Vertex start, int Index){ 

     this.start = start; 
     this.end = end; 
     this.cost = cost; 
     this.Index = Index; 
    } 
     public String toString(){ 
      String result = ""; 
      if(this.start != null && this.end != null){ 
       result = this.Index +","+this.start.Index+","+this.end.Index +","+this.cost; 
      } 
      return result; 
     } 


} 

Answer 1

也許你的文件中包含一個空的或不兼容線？

您可以修復使用的錯誤：

String[] arr = line.split(" "); 
if (arr.length > 3) { 
    result.add(new Edge(Integer.parseInt(arr[0]), //index 
      getPointbyIndex(PointCollection,Integer.parseInt(arr[1])), //start 
      getPointbyIndex(PointCollection,Integer.parseInt(arr[2])), //end 
      Integer.parseInt(arr[3]))); //cost 
    } 
}