Question

I am writing a program to calculate the shortest path between two nodes. In my program I have one custom class called NodeList, which contains an ArrayList of strings (representing nodes) along with a distance. I am using Dijkstra’s algorithm which involves opening up the shortest edge from each node. So, I use this loop to tabulate the possible routes from a given point:

for ( NodeList ed : edges )
    {
     if (ed.nodeList.get(0).equals(node1))
     {
      routes.add(ed);
     }
    }

This works fine, and appears to load the correct values into the variables (according to the debugger). However, when I try and set a variable to the distance of one of the nodes, I get a message “cannot find symbol variable distance”. Here is the code that causes the problem:

int minDistance = routes.get(0).distance;

Is this abnormal or is there something obvious I’m missing?

Answer 1

get(0) apparently returned an object of class type which doesn’t have the particular field.

There are several solutions depending on the root cause of the problem:

• Parameterize the list if possible (e.g. NodeList<Route> instead of NodeList)
• Cast it to the right type (e.g. int distance = ((Route) routes.get(0)).distance)
• Make the field public (e.g. public int distance;)
• Add a getter (e.g. public int getDistance() { return this.distance; }) and use it.