Choosing which input to store where into an ArrayList? (Read from Scanner)

Question

I'm trying to read in a list of Integers from a scanner, using user input, and store all input into an ArrayList, except the last integer the user inputs, of which I want to store within an Integer, (Integer key;) How can I do this?

I've tried putting it into a int[] first but I don't know how many integers the user will input. Is there a way to directly read in all integers to the ArrayList excluding the last one, which would be stored within the Integer key?

What I have so far:

private ArrayList<Integer> theList;
private Integer theKey;
public static void main(String args[])
{
    int[] integers = null;
    System.out.println("Enter a list of integers, the final being a key");
    Scanner scanner = new Scanner(System.in);
    int i = 0;
    try
    {
       while (scanner.hasNext())
       {
         integers[i] = scanner.nextInt();
         i++;
       }
    }
    catch (NullPointerException ex)
    {
    }
    for (int k = 0; i < integers.length; i++)
    {
        System.out.print(integers[k] + " ");
    }


}

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Elliott Frisch Elliott Frisch · Accepted Answer · 2015-12-04T06:38:04

You could use a List<Integer>. Read all of the ints into it, and then (when there are no more ints), remove the last one. Something like,

System.out.println("Enter a list of integers, the final being a key");
Scanner scanner = new Scanner(System.in);
List<Integer> al = new ArrayList<>();
while (scanner.hasNextInt()) {
    al.add(scanner.nextInt());
}
int key = al.remove(al.size() - 1); // <-- the last one is removed, and returned.

Choosing which input to store where into an ArrayList? (Read from Scanner)

2 Answers