String.split() deleting first element

Question

I'm splitting a string of numbers separated by spaces like this :

Integer.valueOf(input.split(" ")[i]);

But if the user inputs 1 2 3 4 5, 2 3 4 5 (there's a space in front of the two) is what comes out. Why is this?
I've tried adding a space to the front of the string with input = " " + input but it just turns out two spaces in front of the 2.

scan.next();
String input = scan.nextLine();
System.out.println(input);
System.out.println(Integer.valueOf(
        input.split(" ")[0]));
for(int i = 0; i < input.length() - 1; i++) {
        nums[i] = Integer.valueOf(
              input.split(" ")[i]);
}

Answer 1

I am assuming you are asking the user to input a sequence of numbers in a single line. So you might get 1 , 2 3 , 52 as the inputted value as a string. You want to store the numbers into an int array. A way to do this is take the string and remove all characters that have nothing to do with the numbers, in this case it are spaces and komma's. There would be a problem if someone enters a 1 , 4 59, but i am ignoring that scenario because it has nothing to do with the question.

String line = scanner.nextLine(); // line = "1 , 2 3 ,  45"

Remove the komma's first:

String result = line.replaceAll("," , " "); // replaces all komma's with a space.

Now you have a string with no komma's To avoid double digit numbers to be converted into 2 single digits, you can use a StringTokenizer.

 StringTokenizer st = new StringTokenizer("this is a test");
     while (st.hasMoreTokens()) {
         System.out.println(st.nextToken());
     }

prints out:

this

is

a

test

We can use this to remove the whitespaces between the numbers in our string or actually only use the values that are read as tokens.

        StringTokenizer resultLine = new StringTokenizer(result);
        int[] numbers = new int[resultLine.countTokens()];
        for (int i = 0; resultLine.hasMoreTokens(); i++) {
            numbers[i] = Integer.parseInt((String) resultLine.nextElement());
        }
        for (int j = 0; j < numbers.length; j++) {
            System.out.print(numbers[j] + " ");
        }
        System.out.println();
    }

Which finally gets us the result we want, an array of integers.

    Scanner s = new Scanner(System.in);
    while (s.hasNext()) {
    String line = s.nextLine();
    String result = line.replaceAll(",", " ");
    StringTokenizer resultLine = new StringTokenizer(result);
    int[] numbers = new int[resultLine.countTokens()];
    for (int i = 0; resultLine.hasMoreTokens(); i++) {
        numbers[i] = Integer.parseInt((String) resultLine.nextElement());
    }
    for (int j = 0; j < numbers.length; j++) {
        System.out.print(numbers[j] + " ");
    }
    System.out.println();
}

Input was: 1 , 2 3 , 52

Output is: 1 2 3 52 // int[] numbers = {1,2,3,52};

I hope this is of some use to you.

Answer 2

When asking "Why doesn't this work the way I expect?" and similar questions, it's always very helpful to provide an MVCE so we can replicate what you're seeing.

Assuming scan is a Scanner and you're not doing additional input processing before the lines you pasted, the unused called to scan.next(), which advances the scanner past the first token of input, is what's muddling your input. Try commenting out that line and input should contain the whole line of text.