Using scanner to get integers and a string from a file

Question

I have a file with contents

v1 0 2 v2 0 3 v3 1 2 v4 1 2 v5 1 3

I need to be able to get the information and store this in three different variables (a String and 2 ints). I am having trouble getting my head around the pattern I would use with the useDelimiter function.

Also is there a way that I don't have to first split it into separate strings, then parseInt from that string? So I have a class called Task which has a String and two Ints. I need to be able to go through the file and create multiple tasks e.g. Task(v1,0,2), Task(v2,0,3).

Thanks.

Answer 1

I think you're over-thinking things -- you don't need to use useDelimiter since Java's Scanner object automatically will split via whitespace.

Scanner scan = new Scanner(new File("myFile"));

ArrayList<Task> output = new ArrayList<Task>();

while (scan.hasNext()) {
    String s = scan.next();
    int num1 = scan.nextInt();
    int num2 = scan.nextInt();
    output.add(new Task(s, num1, num2));
}

Note that the above code will fail if the input does not exactly match the pattern of string-int-int -- the nextInt method in a Scanner will fail if the next token cannot be interpreted as an int, and the code will throw an exception if the number of tokens in the input is not a multiple of three.

Answer 2

Default delimiter is ok

    while(sc.hasNext()) {
        String s = sc.next();
        int i1 = sc.nextInt();
        int i2 = sc.nextInt();
        ...
    }