How to read only valid input

Question

Hi!
I need to validate data. Users can enter either binary, hex, oct or decimal numbers but the program should check for two things length of the number and each digit that constitute the number. For example
the user could mix other chars in a binary number eg. 100g110 or they could do something like 4583y90 for decimal number. i need to check the strings like the one which would contain 100g110, and print error message and ask for another input, now when the user enters a new input i will have to check both of the things again the length and the valid character for that number type...please help...thanks in advance
speedOfLife

Answer 1

I think i got it. Or at least it shouldn't be wildly different than how I think the error should be checked. But, I wish there were an easier and more efficient way to do the same.
please take a look at how i am checking numbers.
I have two functions, they check string length and then check each and every digit to see if they are either (0 or 1) or not. These two functions are being called from the main and after the boolean results are returned from the functions...i m using a while loop to doulbe check if both of the boolean are true...if not then i m throwing error messages...so i mean to say...it works and i m happy but i hate to admit that it took over 6 hours of total time just to do a tiny thing...i wish there was something else i could do...because now i have to do the same kind of coding for hex, decima and octal...please have a look how i did for binary
static boolean getRightSize(String str)throws IOException{
          boolean ok1, ok2;
          ok1 = false;
          ok2 = false;
          long num;
           if (str.length()<=31 )
            ok1 = true;
          else
            ok1 = false;
     return ok1;
   }//end getRightSize()             
     static boolean getValidDigit(String str){
          boolean ok;
          int length = str.length() - 1;
          int l;
          ok = false;
           for ( l = 0; l <= length;  l++ ){
                 if( str.charAt(l) == 48 )
                  ok = true;
                else if(str.charAt(l) == 49 )
                  ok = true;                 
                else
                  ok = false;
           return ok;
     }//end getValidDigit()the main is four times conbined the codes above...which looks messy...
anyway...thanks a lot.
it is fun for me being a rookie...
later