Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
?
Solved

validate char

Posted on 2007-03-26
17
Medium Priority
?
255 Views
Last Modified: 2010-03-31
import java.io.*;

public class validate_char
{
      public static void main(String[] args)throws Exception
      {
            //BufferedReader userInput=new BufferedReader(new InputStreamReader(System.in));
            char gender, input;
            boolean valid;
            do{
            System.out.println("Enter Gender: ");
            input = (char)System.in.read();
                  gender=Character.toUpperCase(input);
                  if (gender !='F' || gender !='M')
                  {
                        System.out.print("Please enter M or F only.");

                  }
                  else

            }while (gender !='F' || gender !='M');

            System.out.println(gender);
      }
}
0
Comment
Question by:dandeliondream
  • 6
  • 5
  • 5
  • +1
17 Comments
 
LVL 3

Author Comment

by:dandeliondream
ID: 18793795
Hi I would like to validate user input. User is allowed to enter F or M only. However, it don't seem to work. Pls advise.
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 18793815
Your question is ..?
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 18793824
You need to use the BufferedReader or Scanner
0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 
LVL 30

Expert Comment

by:Mayank S
ID: 18793832
>> if (gender !='F' || gender !='M')

if (gender !='F' && gender !='M')

>> else

else break ;
0
 
LVL 3

Author Comment

by:dandeliondream
ID: 18793878
It still doesn't work.

Revised code:
import java.io.*;

public class validate_char
{
      public static void main(String[] args)throws Exception
      {
            //BufferedReader userInput=new BufferedReader(new InputStreamReader(System.in));
            char gender, input;
            boolean valid;
            do{
            System.out.println("Enter Gender: ");
            input = (char)System.in.read();
                  gender=Character.toUpperCase(input);
                  if (gender !='F' && gender !='M')
                        System.out.print("Please enter M or F only.");
                        else break;
            }while (gender !='F' && gender !='M');

            System.out.println(gender);
      }
}
0
 
LVL 30

Expert Comment

by:Mayank S
ID: 18793930
What is the value of input being read? Try printing it and see:

>> input = (char)System.in.read();
>> gender=Character.toUpperCase(input);

input = (char)System.in.read();
System.out.println ( "Input: " + input ) ;
gender=Character.toUpperCase(input);
System.out.println ( "Gender: " + gender ) ;
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 18793972
           BufferedReader userInput=new BufferedReader(new InputStreamReader(System.in));
            String gender = null;
            do{
                                          System.out.print("Enter Gender  (Please enter M or F only): ");
                                          gender = userInput.readLine();
            }while ("mMfF".indexOf(gender) < 0);

            System.out.println(gender);
0
 
LVL 3

Author Comment

by:dandeliondream
ID: 18793987
Output:Enter Gender:
q
Please enter M or F only. Enter Gender:
Please enter M or F only. Enter Gender:
Please enter M or F only. Enter Gender:
m
M

I only want 1 error message "Please enter M or F only. Enter Gender:" but the program repeats 3 times.
0
 
LVL 30

Expert Comment

by:Mayank S
ID: 18794005
Works on my machine if I enter M.
0
 
LVL 30

Assisted Solution

by:Mayank S
Mayank S earned 200 total points
ID: 18794021
Oh that is probably due to storage of characters in the input buffer. Use a BufferedReader as CEHJ said and it'll clear it for you.
0
 
LVL 3

Author Comment

by:dandeliondream
ID: 18794030
it works if user enters F,f,m or M. However, when i type in other character, the error message is displayed 3 times. i want only 1 error message to display.
0
 
LVL 3

Author Comment

by:dandeliondream
ID: 18794056
i want the last printIn to display big cap F or M.
0
 
LVL 30

Expert Comment

by:Mayank S
ID: 18794064
Try with the BufferedReader code
0
 
LVL 86

Accepted Solution

by:
CEHJ earned 800 total points
ID: 18794499
>>i want the last printIn to display big cap F or M.

gender = gender.toUpperCase();
0
 
LVL 92

Expert Comment

by:objects
ID: 18796325
your code is reading the eol markers and thus displaying error message for q, \n and \r
uncomment the BfferedReader line you already have and use its readLine(*) method instead of System.in directly to correctly handle eol

            input = userInput.readLine();
            if (input.length()==0)  // added check for empty input
                System.out.print("Please enter M or F");
            } else {
                gender=Character.toUpperCase(input.charAt(0));
                ...
0
 
LVL 3

Author Comment

by:dandeliondream
ID: 18799629
thanks CEHJ and mayankeagle...
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 18800210
:-)
0

Featured Post

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Java Flight Recorder and Java Mission Control together create a complete tool chain to continuously collect low level and detailed runtime information enabling after-the-fact incident analysis. Java Flight Recorder is a profiling and event collectio…
The purpose of this article is to demonstrate how we can use conditional statements using Python.
This theoretical tutorial explains exceptions, reasons for exceptions, different categories of exception and exception hierarchy.
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
Suggested Courses

580 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question