Thread print single digits of number

class p3 extends Thread
{
    static String str_no;
    static public void set_no(String n)
    {
        str_no=n;
    }
    public void run()
    {
        char ch[]=str_no.toCharArray();//convert string to char array
        for(int i=0;i<str_no.length();i++)
        {
            try
            {
                Thread.sleep(1000);
            }
            catch(Exception ex)
            {
                System.out.println(ex);
            }
            System.out.println(ch[i]);
        }
    }

    public static void main(String args[])
    {
        p3 p=new p3();
        if(args.length==0)
        {
            System.out.println("Please enter argument");
        }
        else if(args.length > 1)
        {
            System.out.println("Enter only 1 argument and its number type");
        }
        else
        {
            p3.set_no(args[0]);
            p.start();
        }
    }
}