Secondary input bug within times tables game,

[Martyn]

Hello,

Im having a "secondary input bug" (dont know how else to describe it). I have created a times table program -

- Option 1 Show the 5's times tables.
- Option 2 Play the 5's times tables.
- Option 3 Answer random times table questions
- Option 4 Exit program.

Im sure all the vetran programmers know this one. The problem occurs after selecting option 1 for the second time, you select it option one and then select 5 to show the 5 times tables the cycle then finishes then you are presented with the menu again and you select option 1 but this time you put a non-numerical value i.e. kljbnkadba, from there the try/catch statement kicks in but the program also goes on and prints out the 5 times tables again.

I put a System.exit(1); after the catch but it brings up red writing Java result ##

The easiest way to see what I mean is to run the code, its a tricky one to explain.

Does anyone have any solutions for this?

All ideas are welcome

Thanks

Martyn


Results

run:
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
1
Select times table to view (Between 1 and 12 only)...
5
5 * 1 = 5
5 * 2 = 10
5 * 3 = 15
5 * 4 = 20
5 * 5 = 25
5 * 6 = 30
5 * 7 = 35
5 * 8 = 40
5 * 9 = 45
5 * 10 = 50
5 * 11 = 55
5 * 12 = 60
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
1
Select times table to view (Between 1 and 12 only)...
marty
Invalid data entry, please try again Try Catch ststement kicking in
5 * 1 = 5
5 * 2 = 10
5 * 3 = 15
5 * 4 = 20
5 * 5 = 25
5 * 6 = 30
5 * 7 = 35
5 * 8 = 40
5 * 9 = 45
5 * 10 = 50
5 * 11 = 55
5 * 12 = 60
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package testing;

/**
 *
 * @author pc user
 */
import java.util.Scanner;

public class Testing {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        //Scan for user input
        Scanner scanner = new Scanner(System.in);

        // Initialise variables
        int option = 0;
        int choice = 0;
        int userAnswer = 0;
        int answer = 0;
        int exactAnswer = 0;
        int i = 0;
        int randomNumber1 = 0;
        int randomNumber2 = 0;
        int correctAnswer = 0;
        int correctCrt = 0;

        //Output option menu to user
        do {
            System.out.println("Multiplication tables game\n");
            System.out.println("1... Times tables - (select and view)");
            System.out.println("2... Practice - (select and practice)");
            System.out.println("3... New game - (12 random times table sums)");
            System.out.println("4... Quit");

            //Try non-numerical data entries
            try {

                //read in the value choosen
                option = scanner.nextInt();

                //Catch non-numerical data entries
            } catch (Exception ex) {
                System.out.println("Invalid data entry, please try again ");
                
            }
            //Initialise option selection
            switch (option) {
                /**
                 * Option/Case 1 enables the user to select a times table to view i.e enter 5 to
                 * view the 5's times tables.
                 */
                case 1://Initialise option 1 if user inputs option 1
                    //Try non-numerical data entries
                    try {
                        //Scan for user input after option 1 has been selected
                        Scanner case1 = new Scanner(System.in);

                        //Output statement below once option 1 hase
                        System.out.println("Select times table to view (Between 1 and 12 only)...");

                        //Read in user input
                        choice = case1.nextInt();

                        //Catch non-numerical data entries
                    } catch (Exception ex) {
                        System.out.println("Invalid data entry, please try again ");
                        //System.exit(1);
                    }

                    //Make sure the number entered falls within the limits of 1 & 12
                    if (choice >= 1 && choice <= 12) { //Enter code to write multiplication selected

                        //Loop to execute code and output statement
                        for (i = 1; i <= 12; i++) {
                            System.out.println(choice + " * " + i + " = " + choice * i);
                        }
                    }
                    if (choice <= 0 || choice >= 13) {
                        System.out.println("Please enter a number within the range of 1 & 12");
                    }
                    continue;//Return to start menu when cycle has completed

                  case 4:
                    option = 4; //Initialise option 4 if user inputs option 4
                    //Output statement when user selects option 4
                    System.out.println("Thank you for playing bye...");
                    continue;      //End program if user selects option 4

                //Output statement if user enters invalid selection
                default:
                    System.out.println("Please enter a valid option");
            }
        } while (option != 4);
    }//End of Main Method
}//End of Class Method

Any help would be great on this

[Fubarable]

Why are you using more than one Scanner object? I think you would be far better off sticking to only one for this application.

[Norm]

Remember from your earlier posting of problems with this program, you need to call nextLine() after calls to nextInt() to clear out Scanner's buffer.

You should call the printStackTrace() method in your catch block so you know exactly what the exception is.

What do you want the program to do when there is an exception?

[Martyn]

Hello gents,

Thanks for the feedback, I tried both of your suggestions and I now have an infinite loop, any thoughts?

Thanks

Martyn

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package testing;

/**
 *
 * @author pc user
 */
import java.util.Scanner;

public class Testing {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        //Scan for user input
        Scanner scanner = new Scanner(System.in);

        // Initialise variables
        int option = 0;
        int choice = 0;
        int userAnswer = 0;
        int answer = 0;
        int exactAnswer = 0;
        int i = 0;
        int randomNumber1 = 0;
        int randomNumber2 = 0;
        int correctAnswer = 0;
        int correctCrt = 0;

        //Output option menu to user
        do {
            System.out.println("Multiplication tables game\n");
            System.out.println("1... Times tables - (select and view)");
            System.out.println("2... Practice - (select and practice)");
            System.out.println("3... New game - (12 random times table sums)");
            System.out.println("4... Quit");

            //Try non-numerical data entries
            try {

                //read in the value choosen
                option = scanner.nextInt();
                scanner.nextLine();

                //Catch non-numerical data entries
            } catch (Exception ex) {
                System.out.println("Invalid data entry, please try again ");

            }
            //Initialise option selection
            switch (option) {
                /**
                 * Option/Case 1 enables the user to select a times table to view i.e enter 5 to
                 * view the 5's times tables.
                 */
                case 1://Initialise option 1 if user inputs option 1
                    //Try non-numerical data entries
                    try {
                        //Scan for user input after option 1 has been selected
                        //Scanner case1 = new Scanner(System.in);

                        //Output statement below once option 1 hase
                        System.out.println("Select times table to view (Between 1 and 12 only)...");

                        //Read in user input
                        choice = scanner.nextInt();
                        scanner.nextLine();

                        //Catch non-numerical data entries
                    } catch (Exception ex) {
                        System.out.println("Invalid data entry, please try again ");
                        //System.exit(1);
                    }

                    //Make sure the number entered falls within the limits of 1 & 12
                    if (choice >= 1 && choice <= 12) { //Enter code to write multiplication selected

                        //Loop to execute code and output statement
                        for (i = 1; i <= 12; i++) {
                            System.out.println(choice + " * " + i + " = " + choice * i);
                        }
                    }
                    if (choice <= 0 || choice >= 13) {
                        System.out.println("Please enter a number within the range of 1 & 12");
                    }
                    continue;//Return to start menu when cycle has completed

                  case 4:
                    option = 4; //Initialise option 4 if user inputs option 4
                    //Output statement when user selects option 4
                    System.out.println("Thank you for playing bye...");
                    continue;      //End program if user selects option 4

                //Output statement if user enters invalid selection
                default:
                    System.out.println("Please enter a valid option");
            }
        } while (option != 4);
    }//End of Main Method
}//End of Class Method

[Norm]

I now have an infinite loop

Where is the loop?

Show the program's output

[Martyn]

Hi Norm heres the first five outputs, thanks

run:
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
1
Select times table to view (Between 1 and 12 only)...
marty
Invalid data entry, please try again
Please enter a number within the range of 1 & 12
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
Invalid data entry, please try again
Select times table to view (Between 1 and 12 only)...
Invalid data entry, please try again
Please enter a number within the range of 1 & 12
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
Invalid data entry, please try again
Select times table to view (Between 1 and 12 only)...
Invalid data entry, please try again
Please enter a number within the range of 1 & 12
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
Invalid data entry, please try again
Select times table to view (Between 1 and 12 only)...
Invalid data entry, please try again
Please enter a number within the range of 1 & 12
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
Invalid data entry, please try again
Select times table to view (Between 1 and 12 only)...
Invalid data entry, please try again
Please enter a number within the range of 1 & 12

[Norm]

Are you clearing the Scanner class's buffer so that the invalid data is removed and does not trigger another exception when you use nextInt with invalid input? I mentioned using nextLine() earlier as a means to clear the buffer.

[Martyn]

Hi Norm,

I added -

option = scanner.nextInt();
scanner.nextLine();

But it doesnt seem to be clearing the buffer

Have I done this right?

Thanks

[Norm]

What line in the program is throwing the exception?
How many calls to the nextInt() method were made before the exception?
Do all of those calls have a call to nextLine()?
What if the use inputs bad data? How and where are you going to clear it?

[Martyn]

Hi Norm thanks for your help I will have to investigate the code a bit further to see/understand what is going on i will post online either way.

Thanks again

Martyn

[Martyn]

Hi,

I think I have fixed the cycle problem by adding System.exit(); after the try/catch statements the output is now -

Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
1
Select times table to view (Between 1 and 12 only)...
2
2 * 1 = 2
2 * 2 = 4
2 * 3 = 6
2 * 4 = 8
2 * 5 = 10
2 * 6 = 12
2 * 7 = 14
2 * 8 = 16
2 * 9 = 18
2 * 10 = 20
2 * 11 = 22
2 * 12 = 24
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
1
Select times table to view (Between 1 and 12 only)...
jimbob
Invalid data entry, please try again
Java Result: 13
BUILD SUCCESSFUL (total time: 9 seconds)


Is the red java 13 supossed to print?

Is this acceptable?

Thanks

Martyn

[Norm]

Is the red java 13 supossed to print?

What program is printing that message? How are you executing the program? Some IDEs can add extra messages.

[Martyn]

Im using netbeans 6.9.1, Im not sure what you mean by "how are you executing the program?" can you explain this please?

[quad64bit]

Im using netbeans 6.9.1, Im not sure what you mean by "how are you executing the program?" can you explain this please?

Some people use the command line, some use an application server, some use an IDE. I think that is what we were getting at. You're executing via the big green play button in netbeans I assume :D

If that is the case, norm is asking about what the console output was from netbeans, in its entirety please!

[Martyn]

Thanks for the feedback this is the output in its entirety -

Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit.
1
Select times table to view (Between 1 and 12 only)...
2
2 * 1 = 2
2 * 2 = 4
2 * 3 = 6
2 * 4 = 8
2 * 5 = 10
2 * 6 = 12
2 * 7 = 14
2 * 8 = 16
2 * 9 = 18
2 * 10 = 20
2 * 11 = 22
2 * 12 = 24
Multiplication tables game

1... Times tables - (select and view)
2... Practice - (select and practice)
3... New game - (12 random times table sums)
4... Quit
1
Select times table to view (Between 1 and 12 only)...
jimbob
Invalid data entry, please try again
Java Result: 13
BUILD SUCCESSFUL (total time: 9 seconds)