Filtering java.util.Scanner input?

Question

I'm using a java.util.Scanner , and I want to filter out user input if it is out of range, for example only accept 0, 1, 2 or 3. Perhaps something like:

if !(sc.hasNextInt 0,1,2,3

I'm aware this isn't valid syntax, but I wanted to show what I was going for. How do I tell Java not to store user input that doesn't meet my criteria?

Answer 1

This is something you have to implement yourself -- it's not something Scanner supports. A typical way is to have some sort of loop like this:

int input;
do {
    input = sc.nextInt();
} while (input < 0 || input > 3);

Answer 2

public class Test1
{
    public static void main(String [] args)
    {
        List<Integer> lst= new ArrayList<Integer>();
        //Take user input any number of times based on your condition.

        System.out.println("Please enter a number :");
        Scanner sc= new Scanner(System.in);
        int i= sc.nextInt();
        if(i==0 || i==1 || i==2 ||i==3)
        {
            lst.add(i);
        }
        //Go back
    }
}

Answer 3

    public static void main(String[] args) throws AWTException, Exception {

            Scanner  sc = new Scanner(System.in);
            while(sc.hasNextInt())
            { int val= sc.nextInt();
                if(val==0||val==1 || val==2||val==3)
                {
                    // your code here

                }
               else
                {
                    System.out.println("wrong number, enter again");
                }
            }
        }