Error incrementing value in catch block

[S Gregg]

Hey guys can someone please help me to figure out why my error variable refuses to increment in my catch block. I need it to increment because I need to give the user 2 chances to enter the correct code and if they do not then the program calculates the values it has and quits. In it's current form, it runs fine and will calculate the value and will throw the exception and handle it accordingly except for the error variable. Due to this when i make this change to my while condition,

while (error < 3 || continueLoop)

to check for the number of errors and if I need to exit the loop or not, the program gets stuck in an infinite loop. Here is the code I have.

 int count,i = 0,error = 0;

        Scanner scanner = new Scanner( System.in ); // scanner for input
        boolean continueLoop = true; // determines if more input is needed
        System.out.println("How many values would you like to add");
        count = scanner.nextInt();
        Float[] data = new Float[count];
        System.out.println("Enter each value followed by the 'Enter' key.");
        
        while (continueLoop) {
        
            try //
            {
                for (;i < count;i++) {
                    data[i] = scanner.nextFloat();
                }
                continueLoop = false;

            } // end try
            catch ( InputMismatchException inputMismatchException )
            {
                error++;
                scanner.nextLine(); // discard input so user can try again
                System.out.println("Exception: " + inputMismatchException);
                System.out.println("You must enter floating point values. Please try again.");
            } // end catch


        } // end do...while

        Sum obj = new Sum();
        obj.add(count,data);
        System.out.println("The sum of the values entered is " + obj.getSum());

[Lorand Komaromi]

error < 3 && continueLoop

[S Gregg]

Lorand Komaromi wrote:error < 3 && continueLoop

Wouldn't this mean that both conditions have to be false for the loop to exit. I want to exit if only one of them is false. This still doesn't help with the error variable not incrementing though

[John de Michele]

'S':

No, logical AND (&&) will fail if either the left or right side is false. AND is only true if both sides are true.

John.

[S Gregg]

John de Michele wrote:'S':

No, logical AND (&&) will fail if either the left or right side is false. AND is only true if both sides are true.

John.

But I want it to fail if one or the other is false. If you dont enter the right input the loop should end or if the program runs all the way to the end (which is the continueLoop = false) the loop should exit

[John de Michele]

'S':

That's why you want to use AND. An AND will fail (== false) if one or the other (or both) is false. So, if your error count is three or more it will fail. It will also fail if continueLoop is false. If both of them are false, it will fail, too. If you use OR, your check will fail only if both your error count is three or more and continueLoop is false.

John.

[S Gregg]

John de Michele wrote:'S':

That's why you want to use AND. An AND will fail (== false) if one or the other (or both) is false. So, if your error count is three or more it will fail. It will also fail if continueLoop is false. If both of them are false, it will fail, too. If you use OR, your check will fail only if both your error count is three or more and continueLoop is false.

John.

ok. Point taken but does anyone know why error will not increment when the exception is caught

[Steve Luke]

S Gregg wrote:

John de Michele wrote:'S':

That's why you want to use AND. An AND will fail (== false) if one or the other (or both) is false. So, if your error count is three or more it will fail. It will also fail if continueLoop is false. If both of them are false, it will fail, too. If you use OR, your check will fail only if both your error count is three or more and continueLoop is false.

John.

ok. Point taken but does anyone know why error will not increment when the exception is caught

Why do you think error isn't incrementing with the exception? Nothing in the code you provided tests it.

<edit>
Ok, I see, because when you have while(error<3 || continueLoop), and that condition never returned false to stop the loop. That isn't because error isn't incrementing, it is because continueLoop is true. With the || (OR) operator, the expression is true as long as at least one of the conditions is true. In this case, when error < 3 returns false continueLoop is still true so the loop is allowed to continue. This is why you need to may the comparison using && (AND) because you only want the loop to continue when there are both < 3 errors AND continueLoop is true.

[S Gregg]

Steve Luke wrote:

Why do you think error isn't incrementing with the exception? Nothing in the code you provided tests it.

<edit>
Ok, I see, because when you have while(error<3 || continueLoop), and that condition never returned false to stop the loop. That isn't because error isn't incrementing, it is because continueLoop is true. With the || (OR) operator, the expression is true as long as at least one of the conditions is true. In this case, when error < 3 returns false continueLoop is still true so the loop is allowed to continue. This is why you need to may the comparison using && (AND) because you only want the loop to continue when there are both < 3 errors AND continueLoop is true.

Well that and the fact that I use Netbeans and set up a watch and it never changes from 0. So now I changed to && and I also decided to decrement count so the loop wouldnt quit after 2 correct entries and one incorrect one and im having another issue. I enter 3 for the number of values then I enter 2, 3 and i and the loop quits.

  int count,i = 0,error = 0;

        Scanner scanner = new Scanner( System.in ); // scanner for input
        boolean continueLoop = true; // determines if more input is needed
        System.out.println("How many values would you like to add");
        count = scanner.nextInt();
        Float[] data = new Float[count];
        System.out.println("Enter each value followed by the 'Enter' key.");
        
        while (error < 2 && continueLoop) {
        
            try //
            {
                for (;i < count;i++) {
                    data[i] = scanner.nextFloat();
                }
                continueLoop = false;

            } // end try
            catch ( InputMismatchException inputMismatchException )
            {
                scanner.nextLine(); // discard input so user can try again
                System.out.println("Exception: " + inputMismatchException);
                System.out.println("You must enter floating point values. Please try again.");
                error =  error + 1;
                count = count - 1;
            } // end catch


        } // end do...while

        Sum obj = new Sum();
        obj.add(count,data);
        System.out.println("The sum of the values entered is " + obj.getSum());  

[S Gregg]

Well thank you guys very much for your help but I think I figured it out, I had a couple things that needed to be fixed, using AND instead of OR was one of them

[PrasannaKumar Sathiyanantham]

thats great.....

Be sure to design the program first and then code it....(it saves a lot of time)

[Somnath Mallick]

Would like to ask that you want to give the user 2 tries per entry or two tries on a whole. If you are giving two attempts per entry then the value of error should be initialized to 0 every time the user enters a correct value.

[S Gregg]

PrasannaKumar Sathiyanantham wrote:thats great.....

Be sure to design the program first and then code it....(it saves a lot of time)

I did design the program first but it didn't work out the way had hoped it would so I had to go back to the drawing board and time was running out

Somnath Mallick wrote:Would like to ask that you want to give the user 2 tries per entry or two tries on a whole. If you are giving two attempts per entry then the value of error should be initialized to 0 every time the user enters a correct value.

I realized this error a few hours befre I turned the assignment in and corrected it but thank you.

Here was what I ended up with.

          int count,i = 0,error = 0; //initialise variables

        Scanner scanner = new Scanner( System.in ); // scanner for input
        boolean continueLoop = true; // determines if more input is needed
        System.out.println("How many values would you like to add");
        count = scanner.nextInt(); //accept from user the numbe rof values they would like to enter
        Float[] data = new Float[count]; //create new array to store values
        System.out.println("Enter each value followed by the 'Enter' key.");

        //while there is less than 3 errors caught AND continueLoop is true
        while (error < 3 && continueLoop) {
        
            try 
            {
                for (;i < count;i++) { //accept the number of variables the user enetered
                    data[i] = scanner.nextFloat(); //store them in the array
                    error = 0; //if there was no exception caught above and execution
                }              //gets to this point then reset the error count to 0
                continueLoop = false; //if the for loop successfully exits then we can exit the while loop

            } // end try
            catch ( InputMismatchException exception ) //if exception is caught
            {
                scanner.nextLine(); // discard input so user can try again
                System.out.println("Exception: " + exception); //print out the exception
                System.out.println("You must enter floating point values. Please try again.");
                error =  error + 1; //increment the error counter
            } 
        } 

        Sum obj = new Sum(); //create new object using Sum class
        obj.add(i,data); //pass the number of variables and the actual variables to the add method
        System.out.println("The sum of the values entered is " + obj.getSum()); //print results