Thread: Need help using JOptionPane/entering valid id#

I am working on allowing a user to enter an ID # using JOptionPane. If the ID is valid, then it will display the ID#, student name, and GPA. If it is not valid, then the window should pop up again to allow the user to enter a valid ID. I have managed to get that far.

I am struggling with once a valid ID # is entered, how do I get the loop to stop? I have tried several different ways, but the code below is the most recent one, and it is still not working! Any help/suggestions to try would be greatly appreciated.

import javax.swing.*;
public class StudentIDArray
{
   public static void main(String[] args)
   {
      String enteredID;
      int idNumber;
      int x = 0; 
      String studentName = "";
      double studentGPA = 0.0; 
      boolean validID = false;
 
      int[] id = {1001, 1002, 1003, 1004, 1005, 1006, 1007, 1008, 1009, 1010};
      String[] names = {"Bob", "Joe", "Fred", "Suzie", "Jane", "Megan", "Frank", "Jill", "Tom", "Judy"};
      double[] gpa = {3.5, 3.32, 3.7, 4.0, 3.72, 3.93, 2.6, 1.95, 2.18, 2.83};
 
      enteredID = JOptionPane.showInputDialog(null, "Enter a four-digit student ID number");
      idNumber = Integer.parseInt(enteredID);
 
      for(x = 0; x < id.length; ++x)
      {
         if(idNumber == id[x])
         {
            validID = true;
            studentName = names[x];
            studentGPA = gpa[x];
         }
      }
 
      if(validID == false)
         JOptionPane.showMessageDialog(null, "You entered an invalid ID number");
      else                   
         JOptionPane.showMessageDialog(null, "You entered " + idNumber + ".\nThe student's name is "
            + studentName + " and the GPA is " + studentGPA);                
   }
}

Originally Posted by Norm

What loop is giving you problems? The for loop should end ok.

It would help if I checked that I posted the correct code that shows the issue!

Once an invalid ID # is entered, I can't figure out how to get it to switch to validID = true, and move on with displaying the student's name and GPA. For example, when I enter 1234, it shows an error and asks me to enter another ID number. I enter 1005 (which is on the list of Student ID #'s), it still shows as an error and want me to enter another number. It keeps doing that until I close it.

while(validID == false)
      {
         enteredID = JOptionPane.showInputDialog(null,"You entered an invalid ID number.  Please enter a student ID #");
         idNumber = Integer.parseInt(enteredID);
         for(x = 0; x < id.length; ++x)
         {
            if(idNumber == id[x])
            {
               validID = true;
               studentName = names[x];
               studentGPA = gpa[x];
            }
            else
               validID = false;
         }
      }

Thanks for the feedback. I tried a couple different ways like you mentioned, but I'm wondering if I am not putting the information in the correct place.

When I used just the break statement, it let me enter a new ID # the second time, but regardless of what I entered, it kicked it out and left the name & GPA as the default values. I tried putting the break statement in a couple different places, but none of them were making it work the way I want it to work. I'm just confused on what would be causing the validID to change back to false after I enter a valid ID #, and cause the loop to continue to execute.

for(x = 0; x < id.length && validID == false; ++x)
      {
         if(idNumber != id[x])
         {
            validID = false;
            enteredID = JOptionPane.showInputDialog(null,"You entered an invalid ID number.  Please enter a student ID #");
            idNumber = Integer.parseInt(enteredID);
         }
         else
         {
            studentName = names[x];
            studentGPA = gpa[x];
            validID = true;
            break;
         }
      }

I changed it back to the way I had it in post #3. I made the while statement separate and searched through the array, and it worked! Thanks so much for your help!!