Thread: Saving from csv file and copying contents to a 2D array problems

So I think I am close; however, I am getting some weird output when I print the contents of my array. So the input file is just a text file not an actual csv file but here is what the contents of the input file look like:

A,B,C,D,E,F
∞,1,∞,∞,∞,∞
∞,5,∞,1,11,∞
∞,∞,∞,∞,∞,∞
5,∞,∞,∞,3,∞
∞,∞,∞,11,∞,7
∞,∞,3,∞,∞,∞

Pay no attention to case 2 and 3. Also, I haven't actually built any of the algorithms I just want to build them from the contents of my 2D array but first i need to make sure those contents are correct. So here is my code:

public class GraphAlgorithms {
 
    public static void main(String[] args) throws IOException {
 
        GraphAlgorithms newAlgorithm = new GraphAlgorithms();
 
        String inputFile = "src/input/input.txt";
 
        String[][] readCSV = newAlgorithm.readCSV(inputFile);
 
        Scanner sc = new Scanner(System.in);
 
        System.out.println("Please select the algorithm you wish to run: "
                + "1 for Prim's algorithm, 2 for Kruskal's algorithm"
                + "or 3 for Floyd-Warshall’s algorithm ");
 
        while (sc.hasNext()){
 
            int i = sc.nextInt();
 
            switch(i){
 
                case 1:  
 
                    System.out.println("You chose Prim's algorithm.");
 
                    primsAlgorithm(readCSV);
 
                    break;
 
                case 2:
 
                    System.out.println("You chose Kruskal's algorithm.");
                    break;
 
                case 3:
 
                    System.out.println("You chose Floyd-Warshall's algorithm.");
                    break;
 
                default:
 
                    System.out.println("Invalid entry");
                    break;
            }
 
            System.out.println();
            System.out.println("Please select the algorithm you wish to run: "
                + "1 for Prim's algorithm, 2 for Kruskal's algorithm"
                + "or 3 for Floyd-Warshall’s algorithm ");
        }
 
    }
 
    public static String[][] readCSV(String path) throws FileNotFoundException, IOException {
 
        String fName = path;
            String thisLine;
            FileInputStream fis = new FileInputStream(fName);
            DataInputStream myInput = new DataInputStream(fis);
 
            List<String[]> lines = new ArrayList<>();
 
            while ((thisLine = myInput.readLine()) != null) {
                 lines.add(thisLine.split(","));
            }
 
            // convert our list to a String array.
            String[][] array = new String[lines.size()][0];
            return lines.toArray(array);
 
    }
 
    public static void primsAlgorithm (String [][] array){
 
        for (String[] strings : array) {
 
            for (String string : strings) {
 
                System.out.print("\t" + string);
            }
 
            System.out.println();
        }
    }
}

So the odd part is this is what is being printed when I select 1 as my first option in order to print the array contents:

output.jpg

So the only part of the output that is not expected for me is the two characters printed prior to A. Why is it printing those?

Originally Posted by Norm

How was the input file created? Writing a file as Unicode adds 2 hex characters at the start of a file: ff fe
What program are you viewing the contents of the input file with?
Look at the file with a hex editor to see what the first two bytes are.

Okay yeah that makes sense. As you know the input file is:

A,B,C,D,E,F
∞,1,∞,∞,∞,∞
∞,5,∞,1,11,∞
∞,∞,∞,∞,∞,∞
5,∞,∞,∞,3,∞
∞,∞,∞,11,∞,7
∞,∞,3,∞,∞,∞

However, when I tried saving the notepad file it told me I couldn't save it with the ∞ unless I saved it as Unicode. Should I attempt to find an ANSI ∞ symbol or is there a way to let Java know the incoming file is Unicode so it doesn't insert those two characters?

Originally Posted by Norm

Yes. Several of the io package classes take a charset selector in its constructor. For example: InputStreamReader

Alright great I figured it out. Thanks for your help Norm I appreciate that!