Thread: Help with nested if statements.

Hi there,
I have tried for ages to figure out why this won't work and I think it must be something very
simple, but I'm unable to get it working. After the menu loop the user enters in a valid option, namely A, B, C or X. The only option that works is option A. I'm just trying to get the program functioning at the moment and I'm a beginner programmer so any assistance would be very much appreciated.

//This program allows the user to select from three menu options
//The menu loops back if a valid option isn't chosen and the
//program is exited if the user selects x 
//=====================================
import java.util.Scanner;
 
 
 
public class Assignment1{
   public static void main (String [] args){
      Scanner input = new Scanner(System.in);
 
      char selectedOption = 0;
      char primeNumberChecker = 'A';
      char stampDutyCalculator = 'B';
      char vowelCounter = 'C';
      char exit = 'X';
 
		//Start the menu loop
      while (selectedOption != primeNumberChecker && selectedOption != stampDutyCalculator &&
            selectedOption != vowelCounter && selectedOption != exit)
      {
         //Display application menu to user
         System.out.println("*************** Assignment 1 Menu ****************\n");
         System.out.println(primeNumberChecker + " Prime number checker");
         System.out.println(stampDutyCalculator + " Stamp duty calculator.");
         System.out.println(vowelCounter + " Vowel counter.");
         System.out.println(exit + " exit option.");
         System.out.println("\n**************************************************");
         System.out.println("Please select one of the above options: ");
 
         //Capture selected option
 
         selectedOption = input.next(".").charAt(0);
 
 
 
         if (selectedOption == primeNumberChecker)            
         {
 
            int num;
            System.out.print("Enter an integer value: ");
            num = input.nextInt();
            int i;
            for (i=2; i < num ;i++ )
            {
 
               if (num % i == 0)
                  {
                     System.out.println(num + " is not a prime number!");
                     break;
                  }
            }
            if(i == num)
            {
               System.out.println(num + " is a prime number!");
 
          }else if (selectedOption == stampDutyCalculator) 
          {
            final double THRESHOLD_ONE = 20000;
            final double THRESHOLD_TWO = 115000;
            final double THRESHOLD_THREE = 870000;
            final double THRESHOLD_FOUR = 870001;
 
            double purchasePrice;
            double stampDutyPayable = 0;
            double difference;
 
            System.out.print("Enter a purchase value: ");
 
            purchasePrice = input.nextInt();
 
            if (purchasePrice <= 20000)
            {
                stampDutyPayable = (purchasePrice * 1.4) / 100;
            }else if (purchasePrice > THRESHOLD_ONE && purchasePrice <= THRESHOLD_TWO)
            {
                difference = purchasePrice - THRESHOLD_ONE;
                stampDutyPayable = (THRESHOLD_ONE*1.4) / 100 + (difference*2.4) / 100;
            }else if (purchasePrice > THRESHOLD_TWO && purchasePrice <= THRESHOLD_THREE)
            {
                difference = purchasePrice - THRESHOLD_TWO;
                stampDutyPayable = (THRESHOLD_TWO * 2.4) / 100 + (difference * 6) / 100;
            }else if (purchasePrice >= THRESHOLD_FOUR)
            {
                stampDutyPayable = (purchasePrice * 5.5) / 100;
            }
            System.out.println("Your stamp duty payable: $" + stampDutyPayable);
         }else if (selectedOption == vowelCounter)
         {
            char vCounter[] = new char[5];
 
            vCounter[0] = 'a';
            vCounter[1] = 'e';
            vCounter[2] = 'i';
            vCounter[3] = 'o';
            vCounter[4] = 'u';
 
            //Prompt user to input a string
            int counter = 0;
 
            System.out.println("Enter a string of text: ");
            //Hold the input in the String object aString
            String aString;
            aString = input.nextLine();
            if (aString.isEmpty())
            {
                aString = input.nextLine();
            }
 
            for (int k = 0; k < aString.length(); k++)
            {
                char currentChar = aString.charAt(k);
 
                for (int j = 0; j < vCounter.length; j++ )
                {
                    if (currentChar == vCounter[j])
                    {
                        counter++;
                    }
 
                }
            }
            System.out.println("Number of vowels found in line is " + counter);
         }else if (selectedOption == exit)
         {
            System.out.println("Exiting the program - goodbye...");
         }
 
      }  
    }	
  }	 
}

The only option that works is option A.

Can you explain what the problem is with the other options?
What happens when you try to use them?

Hi Norm,
When I select B,C or X the program terminates.

Your problem is due to incorrect nesting of your if/else if statements.

if (selectedOption == primeNumberChecker)
{
    // snip
    if(i == num)
    {
        System.out.println(num + " is a prime number!");
}else if (selectedOption == stampDutyCalculator)

Due to your indentation it appears that the else if statment is part of the outer if statement. Whereas it is actually the else if to the i==num if statement and therefore inside the outer if statement.

Lol. Thanks heaps for your help Junky. I thought it had something to do with the curly brackets being
positioned incorrectly. There was an extra one down the bottom which should not have been there. Thanks
again for solving my problem.

I have another question regarding this thread. Could someone tell me what I need to do to be able to loop back to the menu options after an option has been selected and executed. At the moment the program just ends after an option has been chosen but I only want it to end when the user selects X. Thank you in advance for your help.

need to do to be able to loop back to the menu options after an option has been selected and executed.

Use a loop that only exits when the user selects an option to exit the loop.

What does your code do now? It has a while loop?

Originally Posted by joon

Could someone tell me what I need to do to be able to loop back to the menu options after an option has been selected and executed. At the moment the program just ends after an option has been chosen but I only want it to end when the user selects X.

while (selectedOption != primeNumberChecker && selectedOption != stampDutyCalculator &&
            selectedOption != vowelCounter && selectedOption != exit)
      {

You have your answer in your while statement.

while(selectedOption != exit)

Oh man, I think I should give up trying to learn programming. I was starring at your sentence for a good 3 minutes before I actually understood. It's so logical but I couldn't figure it out. Thanks for that William.