尝试在多个空格上分割字符串

Question

public Graph(String graphFile) throws IOException {
    int u, v;
    int e, wgt;
    Node t;

    Scanner sc = new Scanner(new File(graphFile));
    String graphType = sc.next();
    boolean undirected = true;
    if (graphType.equals("directed")) {
        undirected = false;
    }

    FileReader fr = new FileReader(graphFile);
    BufferedReader reader = new BufferedReader(fr);

    String splits = " +";  // multiple whitespace as delimiter
    String line = reader.readLine();
    String[] parts = line.split(splits);
    System.out.println("Parts[] = " + parts[0] + " " + parts[1]); // THE ERROR IS THIS LINE

    V = Integer.parseInt(parts[0]);
    E = Integer.parseInt(parts[1]);
}


public class PrimLists {
    public static void main(String[] args) throws IOException {
        int s = 2;
        Scanner sc = new Scanner(System.in);
        System.out.println("enter graph input file name:");
        String file = sc.nextLine();
        Graph g = new Graph(file); // THE ERROR IS THIS LINE
        //Graph g = new Graph(fname);

        g.display();
    }
}

I keep getting the following error

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
    at Graph.<init>(PrimLists.java:170)
    at PrimLists.main(PrimLists.java:315)

I am reading in a text file graph which is this:

9
A
B
C
D
E
F
G
H
I
A B 1
B C 2
C E 7
E G 1
G H 8
F H 3
F D 4
D E 5
I F 9
I A 3
A D 1

Does anyone know why this is not working and could help me out??

Answer 1

This line is not correct

String splits = " +";  // multiple whitespace as delimiter

You probably meant a proper regular expression of

String splits = "\\s+";  // multiple whitespace as delimiter

The problem is that your strings do not contain a literal " +" , and so they were not being split.

Also note that any line that does not have any spaces on it, such as about the first 10 you've shown will error at parts[1] , so you should check parts.length first.