My values during the while loop does not update (Java)

Question

Im trying to keep the FinalBal updated within the while loop but it doesn't. I think I need to add code to keep the FinalBal updated. I'm just praticing for a test. My class in college is basic java. Here is my code:

import java.util.Scanner;

public class TestPraticeBank {


    public static void main(String[] args) {

        int balance = 100;
        int TotalBal;
        int CurBal;
        int amount;

        Scanner keyboard = new Scanner(System.in);
        System.out.print("1. Deposit\n" +
                         "2. Withdrawal\n" +
                         "3. View\n" +
                         "4. Exit\n" +
                         "Enter choice:\n");
        String input = keyboard.nextLine();
        int choice = Integer.parseInt(input);

        while(choice <= 4|| choice >= 5)

        {
            if (choice == 4)
          {
             //System.out.print("Final Balance:"+TotalBal);
             System.exit(choice);
          }
             else if (choice == 3)
            {   
             // System.out.print("Final Balance:"+TotalBal);
            }
             else if (choice == 1)
            {
              System.out.print("Enter the deposit amount:$");
              String deposit = keyboard.nextLine();
              amount = Integer.parseInt(deposit);
              TotalBal = balance + amount;
              System.out.print("Final Balance:$" + TotalBal);
            }
             else if (choice == 2)
            {
              System.out.print("Enter the withdrawal amount:$");
              String withdrawal = keyboard.nextLine();
              amount = Integer.parseInt(withdrawal);
              if (amount <= balance)
                {
             TotalBal = balance - amount;
             System.out.print("Final Balance:$" + TotalBal);
                }
                else
                        {
                           System.out.print("Your withdrawal amount can't be bigger than your current balance");
                        }
            }
            else 
            {
                 System.out.print("Pick only options 1 - 4.");
            }
            System.out.print
                         ("\n1. Deposit\n" +
                         "2. Withdrawal\n" +
                         "3. View\n" +
                         "4. Exit\n" +
                         "Enter choice:\n");
            input = keyboard.nextLine();
            choice = Integer.parseInt(input);
        }  
    }   
}

Answer 1

Not a direct answer, but a matter of style and readability. The switch() statement is a sweeter way of testing the choices in a case like this, especially as some of the choices nest further if statements. And do...while() means you don't have a duplicate input statement to maintain:

int choice;
do {
    choice = Integer.parseInt(input);
    switch(choice) {
        case 1:
            // statements
            break;
        case 2:
            // statements
            break;
        case 3:
            // statements
            break;
        case 4:
            // do nothing
            break;
        default:
            System.out.print("Pick only options 1 - 4.");
            break;
    }
while (choice != 4);
}

As another point of technique, System.exit() is typically used when your normal program flow can't be followed due to unexpected problems. It's usual to construct the logic so that when a user chooses to exit it is graceful, exiting main() rather than saying "oh I give up". You might have memory to release, files to close, threads to stop, servers to log out of, etc. See previous question When should we call System.exit in Java

Answer 2

I'm not going to give you the answer since this is homework, but here are some things to think about:

          CurBal = amount;

This sets CurBal to the amount they typed in.

          CurBal += balance;

What value is balance supposed to hold? Where is it set? Is it supposed to be updated somewhere? Where is it updated?

          TotalBal = CurBal;

At this point, CurBal will be the amount they typed in, plus whatever is in balance. Will this be correct?

          TotalBal =(TotalBal);

What do you think this statement will do, and why is it here? It actually does nothing. Basically it says "take the value in TotalBal and put it into TotalBal".

Answer 3

There are errors in your program.First of all,it's better to use nextInt() method rather than nextLine() and then parseInt(String).It's going to save 2 lines of code.And about your problem.... Now,in case of a deposit,the deposit amount is added to the initial balance.So,it is going to be balance+=CurBal.The same applies to withdrawal.This total balance is not "CurBal" here, it is the balance after deposit or withdrawal.And one more thing,you wish to perform deposit or withdrawal operations.I do not think there is any need of the variable "CurBal" here.So,it is going to be like this:-

int deposit=keyboard.nextInt();
balance+=deposit;
TotalBal=balance;

And for the withdrawal:-

int withdrawal=keyboard.nextInt();
balance-=withdrawal;
TotalBal=balance;

I think it's better to use this.So,give it a try.