Array Index Issue In Java

Question

I am working on a program to implement Kruskal's algorithm on a minimum spanning tree. I have this as my main method inside my Kruskal.java file.

public static void main(String[] args) {
  In in;
  in = new In(args[0]);
  EdgeWeightedGraph G = new EdgeWeightedGraph(in);
  Kruskal mst = new Kruskal(G);
  for (Edge e : mst.edges()) {
        StdOut.println(e);
   }
    StdOut.printf("%.5f\n", mst.weight());
}

The problem I am having is when I try to run the program, I receive an array out of bounds exception. The exception originates from the

in = new In(args[0]);

line. I know that an array out of bounds exception occurs when, in simplified terms, when the program tries to load more items into the array than it has space for. This ultimately causes it to go "out of bounds". In the main method below, EdgeWeightGraph references another class in the program, EdgeWeightGraph.java. I believe it is being populated from the EdgeWeightedGraph class but I am not entirely sure. Any advice on how to fix this array out of bounds exception?

EDIT: Here is a link to the In.java file that I am using: http://algs4.cs.princeton.edu/12oop/In.java.html and here is my Kruskal class that the code from above comes from http://algs4.cs.princeton.edu/43mst/KruskalMST.java.html

NO, an IOoBE happens when you try to access an element that doesn't exist in the array. Are you passing command line args? — ChiefTwoPencils, Nov 05 '15 at 23:47
Post the code of the In class as well as the stack trace. Index out of bounds happens when you attempt to access an index that's not in array. ie index 10 when array is length 10, index 10 is the 11th element. — Dave S, Nov 05 '15 at 23:48
If you're running it with an IDE the link in the answer below will probably not be that helpful. — ChiefTwoPencils, Nov 05 '15 at 23:53
Possible duplicate of [java.lang.ArrayIndexOutOfBoundsException: 0](http://stackoverflow.com/questions/23456742/java-lang-arrayindexoutofboundsexception-0) — Tom, Nov 05 '15 at 23:56

score 2 · Answer 1 · answered Nov 05 '15 at 23:51

The error is simply occuring cause you are not passing any argument while running the main method of the given class.

So when the jre runs the following statement

in = new In(args[0]);

It doesn't get any passed arguments in the args array at 0th position; which results in this error.

Pass the argument and you won't have this error anymore.

To learn about how to correctly pass arguments to main method, refer the java documentation.

Array Index Issue In Java

1 Answers1