Whats wrong with this while loop? [duplicate]

Answer 1

Others have pointed out the bug, but your code is scary in other ways that will eventually trip you up:

if (!(s>=0 && s<=2)) System.out.println ("try again not a valid response") ; 
else r = true ; 

That's bad because you can easily intend more than one statement to run in the case of the if or else clause. Use curly braces and avoid placing conditional statements on a single line:

if (!(s>=0 && s<=2))
{
    System.out.println ("try again not a valid response");
}
else
{
    r = true;
}

It's easier to read and far less likely to introduce hard-to-see bugs.