CODEWITHSUNDEEP
javaswitch-statementjava.util.scanner
Milo Cowell
Milo Cowell

Reputation: 37

Java.util.scanner only seems to be reading certain lines

I am writing a program (according to a specification) that reads a file and uses it to create a simulation of robots in a warehouse. I have used a scanner to read the file and a switch statement to perform the right actions, but only certain cases are being executed.

Here is the code I am having trouble with:

private static void readFromFile() {

        Scanner input = null;

        float capacity = 0;
        float chargeSpeed = 0;

        try {
            input = new Scanner(
                    new File("C:\\Users\\User\\Documents\\Uni\\Java Projects\\Kiva\\configs\\twoRobots.sim"));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        while (input.hasNextLine()) {
            String line = input.nextLine();
            String[] arr = line.split("\\s+"); //regex for whitespace

switch (arr[0]) {
            case "format":
                System.out.println(arr[0]);
                break;
            case "width":
                System.out.println(arr[0]);
                break;
            case "height":
                System.out.println(arr[0]);
                break;
            case "capacity":
                System.out.println(arr[0]);
                break;
            case "chargeSpeed":
                System.out.println(arr[0]);
                break;
            case "podRobot":
                System.out.println(arr[0]);
                break;
            case "shelf":
                System.out.println(arr[0]);
                break;
            case "station":
                System.out.println(arr[0]);
                break;
            case "order":
                System.out.println(arr[0]);
                break;
            }

            line = input.nextLine();
        }

And here is the file (tworobots.sim):

format 1
width 4
height 4
capacity 50
chargeSpeed 1
podRobot c0 r0 3 1
podRobot c1 r1 3 3
shelf ss0 2 2
station ps0 0 2
order 13 ss0

And here is the output (all the actions should be listed):

format
height
chargeSpeed
podRobot
station
order

Why is this? Any help would be much appreciated.

Upvotes: 0

Views: 70

Answers (2)

Srinivas Lakshman
Srinivas Lakshman

Reputation: 489

The extra line is present in the end.

line = input.nextLine(); // Remove this line in the end.

Upvotes: 1

Brandon McKenzie
Brandon McKenzie

Reputation: 1685

The problem is in this excerpt:

while (input.hasNextLine()) {
        String line = input.nextLine();
        String[] arr = line.split("\\s+"); //regex for whitespace

    switch (arr[0]) {
           //...
        }

        line = input.nextLine(); // You read the next line and do nothing with it.
    }

All the lines are read, but that extra nextLine call is reading the next line, then doing nothing with it as you immediately read the line after at the start of the loop again. Just remove that second call to fix it.

Upvotes: 1

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