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  1. #1
    jonmackey22 is offline Member
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    Default If/ else statement with arrays

    In the program below I populated three arrays: student id, name, and GPA. The findStudent() method attempts to match users input with the input stored in the studentID array using an if/ else statement. When I use the if/ else statement the else always executes regardless if the IDs match? I am trying to get JOptionPane.showMessageDialog(null, "Incorrect entry"); to print only if the IDs don't match.

    Java Code:
    import javax.swing.*;  //Used for the JOption dialog boxes
    import java.util.*;    //Used for Scanner input
    public class StudentIDArray
     boolean  nameFound = true;
     final int numOfElements = 2;                 //Final int to control to loop for data
     Scanner  keyboard  = new Scanner(;  //Used to accept user input
     String[] firstName = new String[10];          //Array to hold first names
     String[] studentID = new String[10];          //Array to hold student id
     String[] gradeAvg  = new String[10];          //Array to hold grade point average
     int x;
       //Method to input 10 names, 10 student ID numbers, and 10 grade point averages
       public void getInfo()
          for(x = 0; x < numOfElements; ++x)
            //Populate the firstName[] array
            System.out.print("Enter the students first name: ");
            firstName[x] =;
              //Populates the studentID[] array
              System.out.print("Enter their student ID number");
              studentID[x] =;
                //Populates the gradeAvg[] array
                System.out.print("Enter their grade point average");
                gradeAvg[x] =;
       //Method to find a students name and GPA based on a user student ID search
       public void findStudent()
        //Prompts the user for a students ID number
        String id = JOptionPane.showInputDialog(null, "Enter the student's ID number");
          for(int x = 0; x < numOfElements; ++x)
             //If the users input matches the students ID their name is printed with their GPA
               JOptionPane.showMessageDialog(null, "NAME: " +firstName[x]+ "   GPA: " +gradeAvg[x]+"");
               JOptionPane.showMessageDialog(null, "Incorrect entry");    
       //Main method that calls the other methods in the StudentIDArray class
       public static void main(String args[]) 
        StudentIDArray show = new StudentIDArray();

  2. #2
    KevinWorkman's Avatar
    KevinWorkman is offline Crazy Cat Lady
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    Default Re: If/ else statement with arrays

    Time to debug your program. The goal is to figure out exactly what line the program's execution differs from what you expect, and then what the values of every variable on that line are.

    You can do this by stepping through this with a debugger, or by adding print statements, or simply walking through with a piece of paper and a pencil to keep track of variable values.

    I'll give you a hint. Look at this line:


    What is the value of id? What is the value of x? What is the value of studentID[x]?
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  3. #3
    jim829 is offline Senior Member
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    Jan 2013
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    Default Re: If/ else statement with arrays

    Another observation which probably has nothing to do with your problem. You have a boolean nameFound which is set to true. And then you use it in some if statements. But you never change it, thus it is not necessary. I define this stuff as clutter. And it can make your program hard to read and debug.

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  4. #4
    ImTroyMiller is offline Member
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    Jan 2014
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    Default Re: If/ else statement with arrays

    This is what it is, sorry for the multiple edits...

    } else if (x == numOfElements) { other words, you're iterating through the elements(two in your example), and then your not only printing out when you found them, but also printing out when you didn't find them(which is one not found in your example).
    Last edited by ImTroyMiller; 01-29-2015 at 02:23 AM.

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