Input Validation Help

[Spyderpig]

so this is a program that i am writing. how do i make it so that when it asks for how many shares do you want to sell, the input validation makes sure there is only an integer entered rather than eg. a character?

also side note, im not sure why but my tValue isnt changing...

edit** ps: its very late so forgive me for being confusing.

//Any necessary imports
import java.util.*;

public class StockTrader 
{ 
    public static void main(String[] args) 
    {

        // declare and initialize a Scanner
        Scanner in = new Scanner(System.in);
        // get seed value from user and use it to make the random number
        // generator
        System.out.println("Please enter a seed value [integer]:");
        // you may assume the user inputs an int for the seed
        int seed = in.nextInt();
        in.reset();
        Random rng = new Random(seed);

        // declare and initialize any other needed variables
        int pORNG = 100;
        int pMCRO = 100;
        int pGUUG = 100;
        int sORNG = 0;
        int sMCRO = 0;
        int sGUUG = 0;
        int money = 10000;
        int day = 1;
        int tValue = (sORNG * pORNG + sMCRO * pMCRO + sGUUG * pGUUG + money);//why isnt this changing?


        // begin day loop
        while (day < 12) 
        {
            // print daily report
            System.out.println("****************************");
            System.out.println("Day " + day + " - You Currently Have:");
            System.out.println("Money: " + money);
            System.out.println("ORNG Shares: " + sORNG);
            System.out.println("MCRO Shares: " + sMCRO);
            System.out.println("GUUG Shares: " + sGUUG);
            System.out.println("Total Value: " + tValue);
            System.out.println();
            // begin menu loop

            boolean done = false;
            while(!done)
            {
                // prompt user for their decision (buy, sell, or end turn)
                System.out.println("Would you like to:");
                System.out.println("1. Buy");
                System.out.println("2. Sell");
                System.out.println("3. End your trading");
                String userChoice = in.next();

                while (!userChoice.equals("1") && !userChoice.equals("2") && !userChoice.equals("3"))
                {
                    System.out.println("Invalid input: enter 1, 2, or 3.");
                    System.out.println("Would you like to:");
                    System.out.println("1. Buy");
                    System.out.println("2. Sell");
                    System.out.println("3. End your trading");
                    userChoice = in.next();

                }
                // if user chose buy

                if (userChoice.equals("1")) 
                { 
                    // Start buy loop
                    // prompt for which stock to buy
                    System.out.println("Which stock would you like to buy?");
                    System.out.println("1. Orange Inc.");
                    System.out.println("2. Macrosoft");
                    System.out.println("3. Guugle");
                    String iBuy = in.next();

                    while (!iBuy.equals("1") && !iBuy.equals("2") && !iBuy.equals("3"))
                    {
                        System.out.println("Invalid input; enter 1, 2, or 3.");
                        System.out.println("Which stock would you like to buy?");
                        System.out.println("1. Orange Inc.");
                        System.out.println("2. Macrosoft");
                        System.out.println("3. Guugle");
                        iBuy = in.next();

                    }

                    // prompt for how many shares to buy

                    System.out.println("Enter how many shares you would like to buy:");
                    int sBuy = in.nextInt();
                    
                    //if (in.hasNextInt())
                    // update money and shares count
                        if (iBuy.equals("1")) 
                        {
                            int nMoney = pORNG * sBuy;
    
                            while (nMoney > money)
                            {
                                System.out.println("You don't have that much money.");
                                System.out.println("Enter how many shares you would like to buy:");
                                sBuy = in.nextInt();
                                nMoney = pORNG * sBuy;
                            }
    
                            money = money - nMoney;
                            sORNG = sORNG + sBuy;
    
                            System.out.println("You now have " + money + " money.");
                        } 
                        else if (iBuy.equals("2"))
                        {
                            int nMoney = pMCRO * sBuy;
                            
                            while (nMoney > money)
                            {
                                System.out.println("You don't have that much money.");
                                System.out.println("Enter how many shares you would like to buy:");
                                sBuy = in.nextInt();
                                nMoney = pMCRO * sBuy;
                            }
    
                            money = money - nMoney;
                            sMCRO = sMCRO + sBuy;
    
                            System.out.println("You now have " + money + " money.");
                        } 
                        else if (iBuy.equals("3"))
                        {
                            int nMoney = pGUUG * sBuy;
                            
                            while (nMoney > money)
                            {
                                System.out.println("You don't have that much money.");
                                System.out.println("Enter how many shares you would like to buy:");
                                sBuy = in.nextInt();
                                nMoney = pGUUG * sBuy;
                            }
    
                            money = money - nMoney;
                            sGUUG = sGUUG + sBuy;
    
                            System.out.println("You now have " + money + " money.");
                        } 
                    }
                //    else
                //    {
                //        System.out.println("Please enter an integer.");
                //    }
                

                // End buy loop
                // if user chose sell
                
                if (userChoice.equals("2")) 
                {
                    // Start sell loop

                    // prompt for which stock to sell
                    System.out.println("Which stock would you like to sell?");
                    System.out.println("1. Orange Inc.");
                    System.out.println("2. Macrosoft");
                    System.out.println("3. Guugle");
                    String iSell = in.next();
                    
                    while (!iSell.equals("1") && !iSell.equals("2") && !iSell.equals("3"))
                    {
                        System.out.println("Invalid input; enter 1, 2, or 3.");
                        System.out.println("Which stock would you like to sell?");
                        System.out.println("1. Orange Inc.");
                        System.out.println("2. Macrosoft");
                        System.out.println("3. Guugle");
                        iSell = in.next();

                    }
                    // prompt for how many shares to sell
                    System.out.println("Enter how many shares you would like to sell:");
                    int sSell = in.nextInt();
                
                        if (iSell.equals("1")) 
                        {
                            int nMoney = pORNG * sSell;
    
                            while (sSell > sORNG)
                            {
                                System.out.println("You don't have that many shares.");
                                System.out.println("Enter how many shares you would like to sell:");
                                sSell = in.nextInt();
                                nMoney = pORNG * sSell;
                            }
    
                            money = money + nMoney;
                            sORNG = sORNG - sSell;
    
                            System.out.println("You now have " + money + " money.");
                        } 
                        else if (iSell.equals("2"))
                        {
                            int nMoney = pMCRO * sSell;
                            
                            while (sSell > sMCRO)
                            {
                                System.out.println("You don't have that many shares.");
                                System.out.println("Enter how many shares you would like to sell:");
                                sSell = in.nextInt();
                                nMoney = pMCRO * sSell;
                            }
    
                            money = money + nMoney;
                            sMCRO = sMCRO - sSell;
    
                            System.out.println("You now have " + money + " money.");
                        } 
                        else if (iSell.equals("3"))
                        {
                            int nMoney = pGUUG * sSell;
                            
                            while (sSell > sGUUG)
                            {
                                System.out.println("You don't have that many shares.");
                                System.out.println("Enter how many shares you would like to sell:");
                                sSell = in.nextInt();
                                nMoney = pGUUG * sSell;
                            }
    
                            money = money + nMoney;
                            sORNG = sORNG - sSell;
    
                            System.out.println("You now have " + money + " money.");
                        }
                    
            
                    // update money and shares count
            

                    }
                
                // end of loop sell loop
                // if user chose to end turn
                if (userChoice.equals("3")) 
                {
                    done = true;
                }
            }
        

        // update data such that menu loop will end 

        // end menu loop

        // calculate closing prices for Orange Inc., Macrosoft, and Guugle

        int change = rng.nextInt(2);
        int sChange = (int) (Math.random() * 10) +1;

        if (change == 0) 
        {
            pORNG = pORNG + sChange;

            //System.out.println("Orange Inc. Increases by " + sChange);
            //System.out.println("New price is: " + pORNG);
        } 
        else 
        {
            pORNG = pORNG - sChange;
            //System.out.println("Orange Inc. Decreases " + sChange);
            //System.out.println("New price is: " + pORNG);
        }

        int change2 = rng.nextInt(2);
        int sChange2 = (int) (Math.random() * 10) +1;
        // You need to make all the stocks change mang :|
        if (change2 == 0) {
            pMCRO = pMCRO + sChange2;
            //System.out.println("Macrosoft Increases by " + sChange2);
            //System.out.println("New price is: " + pMCRO);
        } 
        else 
        {
            pMCRO = pMCRO - sChange2;
            //System.out.println("Macrosoft Decreases by " + sChange2);
            //System.out.println("New price is: " + pMCRO);
        }
        int change3 = rng.nextInt(2);
        int sChange3 = (int) (Math.random() * 10) +1;
        if (change3 == 0) 
        {
            pGUUG = pGUUG + sChange3;
            //System.out.println("Guugle Increases by " + sChange3);
            //System.out.println("New price is: " + pGUUG);
        } 
        else 
        {
            pGUUG = pGUUG - sChange3;
            //System.out.println("Guugle Decreases by " + sChange3);
            //System.out.println("New price is: " + pGUUG);
        }

        // print end of day report
        System.out.println("Day " + day + " - Closing Prices:");
        System.out.println("Money: " + money);
        System.out.println("ORNG Price: " + pORNG);
        System.out.println("MCRO Price: " + pMCRO);
        System.out.println("GUUG Price: " + pGUUG);
        System.out.println("");
        // end of day loop
        day++;
        }
        // print end-of-game report

        if (day == 12) 
        {
            System.out.println("*******************");
            System.out.println("*******************");
            System.out.println("End of Game Summary");
            System.out.println("Money: " + money);
            System.out.println("ORNG Shares: " + sORNG);
            System.out.println("MCRO Shares: " + sMCRO);
            System.out.println("GUUG Shares: " + sGUUG);
            System.out.println("Total Value: " + tValue);
        }
    }
}

[JosAH]

so this is a program that i am writing. how do i make it so that when it asks for how many shares do you want to sell, the input validation makes sure there is only an integer entered rather than eg. a character?

also side note, im not sure why but my tValue isnt changing...

        // declare and initialize any other needed variables
        int pORNG = 100;
        int pMCRO = 100;
        int pGUUG = 100;
        int sORNG = 0;
        int sMCRO = 0;
        int sGUUG = 0;
        int money = 10000;
        int day = 1;
        int tValue = (sORNG * pORNG + sMCRO * pMCRO + sGUUG * pGUUG + money);//why isnt this changing?

Do your math: tValue = 0*100 + 0*100 + 0*100 + money ( == money )

About the input validation: read a String from the user input stream; in a try-catch block try to Integer.parsInt( ... ) the String; if the input wasn't valid an Exception is thrown; you catch the exception and tell the user about the mistake and try again. If no Exception was thrown you have your int value.

kind regards,

Jos

[Spyderpig]

tValue is being changed throughout the program though. Shouldnt that update those variables?

[JosAH]

tValue is being changed throughout the program though. Shouldnt that update those variables?

I searched your program text for "tValue=" (with and without space(s) before the = sign) but nowhere do you assign it a (new) value. It doesn't change automagically.

kind regards,

Jos