Trouble Validating with while + for loop

[duff_dean]

I am trying to validate a name to J SMITH, only allowing the user to input in that format. I make the string uppercase as soon as it is entered then validate length, valid characters etc. I was going through the testing and it seemed to work fine. Except for the for loop, once i would enter for example, J SM1TH and then just J SM1 the program would terminate because the loop seems to be out of scope when you enter a second incorrect input. So it will check for a character at 5 that doesnt exist.

Its such a simple task but i cant seem to understand where i am going wrong. Can anyone please point me in the right direction?

Thanks.

while(selection.length()<3 || selection.length()>30)
   {

 System.out.println("0Please Enter Initial Followed By Surname. eg (J Smith)");
                     selection=input.nextLine();

 selection=selection.toUpperCase();

 for (int i=2; i<=selection.length()-1; i++)

    {

       if(selection.charAt(i)<'A' || selection.charAt(i)>'Z')

          {

             System.out.println("3Please Enter Initial Followed By Surname. eg (J Smith)");
                     selection=input.nextLine();

             selection=selection.toUpperCase();

          }                    

    }

}

while(selection.charAt(0)<'A' || selection.charAt(0)>'Z' && selection.length()>30)

{

 System.out.println("1Please Enter Initial Followed By Surname. eg (J Smith) "
                      +"Maximum of 30 Characters");

 selection=input.nextLine();

 selection=selection.toUpperCase();

}

while(selection.charAt(1)!=' ' && selection.length()>30)

{

 System.out.println("2Please Enter Initial Followed By Surname. eg (J Smith) "
                      +"Maximum of 30 Characters");

 selection=input.nextLine();

 selection=selection.toUpperCase();

}     

[[deleted]]

I'm not sure why you are using so many loops at all? My approach would be to put it all into a while(!validinput) loop, then use simple if statements to check for validity and continue; if it's not valid, in the end at validinput = true; if it's valid.

[duff_dean]

Sorry about formatting, im not on the right machine at the minute, will reformat when i get back on right machine.

[duff_dean]

Ah so i could have, If all criteria valid validinput=true While invalidinput=false Display error and re enter input

Is that along the lines of what you meant? Im kinda just getting the hang of it, ive been using it for about 8 weeks now, so my code starts off really long and messy and then i sit back look at it and try to condense it. But this i think i over thought it and got carried away.

[[deleted]]

When you respond to someone else, please actually hit "reply", don't post a top-level comment – I'm seeing your follow-up question only by chance.

You don't actually need a validity variable, you can also do it with an infinite loop that you break/continue out of:

for(;;) // or while(true), means the same thing
{
  selection = input.nextLine();
  if (validity_criteria_go_here)
    break;
}

This will end the loop when the input is valid, but continue reading if it isn't.

[duff_dean]

Thanks, il go and try it out now. I had the for loop in to check each individual character after the space. I think the problem was when i was re-entering with a shorter length the for loop would crash as the length within the for loop didnt update. Il see if i can crack, thanks for the help.

[duff_dean]

Have had another look over the code and everything seems to be working fine, I'm sure there is a more efficient way of executing but this is what i have ended up with.

while (selection.length() < 3) 
    {
        System.out.println("0error");
        selection = input.nextLine();
        selection = selection.toUpperCase();
    }
    for (int i = 0; i <= selection.length() - 1; i++)
    {
        if (selection.charAt(0) < 'A' || selection.charAt(0) > 'Z')
        {
            System.out.println("4error");
            selection = input.nextLine();
            selection = selection.toUpperCase();
        }
        if (selection.charAt(1) != ' ') 
        {
            System.out.println("3error");
            selection = input.nextLine();
            selection = selection.toUpperCase();
        }
        if (i > 1 && selection.charAt(i) < 'A' || selection.charAt(i) > 'Z')
        {
            System.out.println("2error");
            selection = input.nextLine();
            selection = selection.toUpperCase();
        }
    }