Java での ATM プログラム

package jex;
import java.util.*;
class ATM {
public static void main( String args[] ) {
//declare and initialize balance, withdraw, and deposit
int balance = 50000;
int withdraw, deposit;
//create scanner class object to get choice of user
Scanner sc = new Scanner(System.in);
while(true)
{
System.out.println( "Welcome to ATM ... " );
System.out.println( "Select 1 for Withdraw" );
System.out.println( "Select 2 for Deposit" );
System.out.println( "Select 3 for Check Balance" );
System.out.println( "Select 4 for EXIT" );
System.out.print( "Select the appropriate options you want to perform:" );
//get the user selected option
int op = sc.nextInt( );
switch( op )
{
case 1: System.out.print( "Enter the amount to be withdrawn :" );
// accept the withdraw amount from the user
withdraw = sc.nextInt();
//check whether the balance is greater than or equal to the withdrawal amount
withdraw( balance, withdraw);
break;
case 2: System.out.print( "Enter the amount to be deposited :" );
//accept the deposit amount from the user
deposit = sc.nextInt();
// call the function and add the deposit amount to the total balance
deposit( balance, deposit );
break;
case 3:
// printing the total balance of the user
printBalance( balance );
System.out.println(" ");
break;
case 4:
// exit from the menu
System.exit( 0 );
}
}
}
// function to print the current balance in an account
public static void printBalance(int balance)
{
System.out.println(" The Current Balance : " + balance);
System.out.println();
}
// The function to Withdraw an amount and update the balance
public static int withdraw(int balance, int withdrawAmount)
{
System.out.println( "Withdrawn Operation :" );
System.out.println("The withdrawing Amount is : " + withdrawAmount);
if (balance >= withdrawAmount) {
balance = balance - withdrawAmount;
System.out.println( "Please collect your money and remove the card" );
printBalance( balance );
}
else {
System.out.println( "Sorry! the balanace is insufficient." );
System.out.println( );
}
return balance;
}
// The function to deposit an amount and update the balance
public static int deposit(int balance, int depositAmount)
{
System.out.println( "Deposit Operation :" );
System.out.println(" The depositing amount is : " + depositAmount);
balance = balance + depositAmount;
System.out.println( "Your Money has been successfully deposited" );
printBalance(balance);
return balance;
}
}